Tag /

Sleep

Sleep Regularity featured article

Most people understand the importance of sleep duration, but there's another critical—and often overlooked—factor that plays a major role in health and performance: sleep regularity. It's not just about how much sleep you get, but how consistently you go to bed and wake up each day.

A growing body of research suggests that erratic sleep schedules—fluctuating bedtimes, wake-up times, and inconsistent sleep durations—can have profound consequences for both physical and mental health.

Irregular sleep patterns have been linked to everything from metabolic dysfunction and cardiovascular disease to mood disturbances, increased risk-taking behaviors, and even cognitive decline. Studies indicate that maintaining a consistent sleep schedule may be just as important as getting enough sleep, if not more. One particularly striking finding is that sleep variability—especially inconsistent wake times—can predict negative health outcomes more strongly than total sleep duration. **People...

Read the full topic article
Jump to related topics

Episodes

exercise

Dr. Andy Galpin: The Optimal Diet, Supplement, & Recovery Protocol for Peak Performance

Posted on April 22nd 2025 (about 2 months)

Dr. Andy Galpin & Dr. Rhonda Patrick discuss nutrition, supplement, and recovery strategies for improving exercise performance.

sleep

This What Losing Just 1 Hour of Sleep for 3 Nights Does to Your Body

Posted on January 21st 2025 (5 months)

In this clip, Dr. Rhonda Patrick explores the effects of sleep deprivation on insulin signaling, diabetes risk, appetite regulation, and metabolic health.

sleep

Don't Get Much Sleep? Here's the #1 Thing You Should Do

Posted on January 20th 2025 (5 months)

In this clip, Dr. Rhonda Patrick discusses how HIIT improves metabolic health and reduces risks associated with sleep restriction.

Topic Pages

  • Melatonin

    Nocturnally secreted melatonin binds MT1/MT2 receptors in the suprachiasmatic nucleus, dampening neural activity and initiating sleep.

  • Sleep Regularity

    Consistent sleep-wake timing entrains circadian rhythms, aligning homeostatic sleep pressure with circadian sleep propensity, thereby improving sleep consolidation.

  • Time-restricted eating

    Time-restricted eating aligns metabolic cues with circadian clocks, strengthening melatonin rhythms and thereby improving sleep quality.

News & Publications

  • The air in children's sleeping areas harbors high chemical pollutant levels, potentially increasing young children's exposure to toxic compounds. pubs.acs.org
    Sleep Development Pollution

    The air around a child’s bed may carry more chemical pollutants than the bedroom itself. A recent study suggests sleeping spaces are a key source of toxic exposure for young children.

    Researchers collected air samples from the sleeping areas and bedrooms of 25 children between 6 months and 4 years old living in Canada. They also tested the children’s mattresses for chemical emissions, looking for three types of compounds: phthalates (used to soften plastics), flame retardants, and UV filters (used in dyes and textiles). These chemicals belong to a group called semivolatile organic compounds, or SVOCs, which can escape from products and linger in air, dust, and on surfaces.

    The researchers detected nearly 30 different chemicals in each of the three sampling locations—bedroom air, sleeping area air, and mattresses. The air in the sleeping area had higher chemical levels than the surrounding bedroom, confirming that bedding and other nearby items were likely contributing to children’s exposure. In many cases, the mattresses themselves released higher amounts of certain phthalates and flame retardants, while bedding appeared to be a major source of flame retardants.

    These findings suggest that young children face increased chemical exposure while they sleep, a substantial concern given how much time they spend in their sleeping environments. The investigators proposed that parents reduce exposure by regularly washing bedding and sleepwear, as fabrics tend to trap airborne chemicals. Furthermore, some textiles can also release chemicals, so having fewer items in the bed is beneficial.

    Read more
  • Resistance training notably improves sleep quality in older adults, outperforming both aerobic and combined exercises. fmch.bmj.com
    Exercise Aging Sleep

    As people age, sleeping problems become more common, often affecting mood, memory, and overall health. A recent study found that resistance training improves sleep in older adults better than other forms of exercise.

    Researchers analyzed 25 clinical trials involving more than 2,100 people to see how different kinds of physical activity influenced sleep quality. They looked specifically at the Pittsburgh Sleep Quality Index, a subjective measure of a person’s sleep quality. The studies compared people who exercised to those who adhered to their usual routines, received health education, or did no physical activity at all.

    Strength training was the most effective approach for improving sleep scores, followed by aerobic activity and then a combination of both. People who engaged in strength exercises were more likely to report better sleep, with the strongest improvement observed across all comparisons. Aerobic activity also helped but wasn’t as effective, and combined exercise had a more modest benefit.

    These findings suggest that resistance training does more than build muscle—it also improves sleep. Resistance training builds bone, too, a critical component of aging well. Learn more in this clip featuring Dr. Brad Schoenfeld.

    Read more
  • Sleep disruption reduces the newly discovered hormone 'raptin,' potentially increasing appetite and promoting weight gain. www.nature.com
    Diet Obesity Sleep Hormones

    Sleepless nights don’t just leave you tired—they may also interfere with your body’s ability to regulate hunger. Researchers have long known that poor sleep increases the risk of obesity, but the biological link has remained elusive. A recent study found that a sleep-triggered hormone called raptin helps control appetite and may explain why people who don’t get enough sleep are more likely to gain weight.

    Researchers examined brain activity, hormone levels, and eating behavior under different sleep conditions in mice and humans. They identified a previously unknown hormone, which they named raptin, and tracked where and when it was released. They also studied the effects of a genetic variant that blocks raptin production and examined hormone levels in people with sleep deficiency, obesity, and nighttime eating syndrome.

    They discovered that raptin is produced in a part of the brain that regulates hunger and hormone secretion and is released during sleep. When sleep is disrupted, raptin levels drop. In lab experiments, raptin acted on specific receptors in the brain and stomach to reduce appetite and slow stomach emptying. People with obesity and sleep deficiency had lower levels of raptin, while those who underwent therapy to improve sleep showed increases in the hormone. A genetic variant that blocks raptin production was linked to night-time overeating and obesity.

    These findings indicate that raptin explains how sleep influences weight gain and appetite. Learn more about the effects of sleep deprivation in Aliquot #27: Health consequences of sleep deprivation, part I: Metabolic & immune health and Aliquot #28: Health consequences of sleep deprivation, Part 2: Mental & cognitive health

    Read more
  • Working night shifts and accumulating sleep debt increase nurses' susceptibility to illnesses, with risk escalating by nearly 50% for frequent night shift workers. www.tandfonline.com
    Sleep Immune System Circadian Rhythm

    Shift work keeps essential services operating, but often at a cost to workers' health. Nurses, who frequently work irregular hours, may be particularly susceptible to disrupted sleep and weakened immune function. A recent study found that sleep debt and night shift work may elevate nurses' risk of common infections by as much as 50%.

    Researchers analyzed data from more than 1,300 nurses (average age, 42 years). Participants reported their typical sleep duration, how much sleep they needed, whether they worked night shifts, and how often they experienced infections, such as colds, pneumonia, sinusitis, or gastrointestinal infections, over the previous three months. The researchers used statistical methods to examine links between sleep patterns, shift schedules, and infection risk while accounting for age, sex, and whether the nurses had children at home.

    Nurses with greater sleep debt faced a higher risk of multiple infections. Those who slept one to two hours less than necessary were about 30% more likely to experience a cold, while those with more than two hours of sleep debt had more than double the risk. The risk of pneumonia, bronchitis, sinusitis, and gastrointestinal infections also rose with greater sleep debt. Working night shifts was linked to a 28% higher risk of experiencing a cold, and those with more frequent night shifts were nearly 50% more likely to report having a cold.

    These findings suggest chronic sleep debt and night shift work compromise the immune system, making nurses more susceptible to infections. Learn about practical ways to manage the risks of shift work in this episode featuring Dr. Satchin Panda.

    Read more
  • Cold-water immersion may offer stress relief and immune benefits, but its effects are highly time dependent. journals.plos.org
    Sleep Inflammation Immune System Mental Health Cold Stress

    Cold-water immersion has surged in popularity, with ice baths and cold showers touted as shortcuts to better health. Advocates claim it improves mood, sharpens focus, and speeds up recovery. A recent study found that while cold exposure temporarily increased inflammation, it reduced stress 12 hours later, improved sleep, and reduced sick days.

    Researchers conducted a systematic review and meta-analysis of 11 studies involving more than 3,100 healthy adults investigating the effects of cold-water exposure on mental and physical health markers, including mood, stress, immunity, inflammation, and sleep quality. Participants in the various studies took cold showers or ice baths at temperatures between 7°C (45°F) and 15°C (59°F) for at least 30 seconds.

    The analysis revealed that inflammation spiked immediately after immersion and stayed elevated for an hour. Interestingly, stress levels dropped 12 hours later but remained unchanged at other time points. Cold exposure did not immediately boost immune function, but a separate analysis linked cold showers to a 29% drop in sickness absence. Participants reported better sleep and overall well-being but no changes in mood.

    These findings suggest that cold-water immersion may offer short-term stress relief and potential immune benefits, with highly time-dependent effects. The effects of cold exposure may be due to hormesis—a compensatory defense response that conditions the body against future stressors. Learn more in Aliquot #97: Thermal Stress, Part II: Unveiling the Power of Cold Exposure on Health and Performance

    Read more
  • Melatonin supplementation may heighten DNA repair in night shift workers during daytime sleep, potentially reducing cancer risk. oem.bmj.com
    Cancer Sleep DNA Damage Circadian Rhythm Melatonin Supplements

    Working night shifts may increase the risk of cancer by disrupting the production of melatonin, a hormone essential for DNA repair. This disruption can impair the body’s ability to repair oxidative DNA damage, potentially contributing to cancer development. A recent study found that melatonin supplementation could improve the repair of oxidative DNA damage in night shift workers.

    The researchers conducted a four-week randomized, placebo-controlled trial with 40 night shift workers, providing them a 3-milligram dose of melatonin before their daytime sleep periods. They collected urine samples during daytime sleep and nighttime work periods, measuring 8-hydroxy-2′-deoxyguanosine (8-OH-dG), a marker of DNA repair capacity.

    They found that melatonin supplementation nearly doubled 8-OH-dG excretion during daytime sleep, indicating improved DNA repair. However, they observed no difference in 8-OH-dG excretion during the night shift. Although the melatonin group experienced a slight decrease in wakefulness after falling asleep, the researchers found no differences in total sleep duration or sleepiness levels between the two groups.

    The findings from this small study suggest that melatonin supplementation enhances oxidative DNA repair in night shift workers, offering the potential for reducing cancer risk. More extensive studies may identify optimal dosages and the long-term effects of melatonin supplementation in this population. Learn about the pros and cons of melatonin supplementation in this clip featuring Dr. Satchin Panda.

    Read more
  • Misaligned sleep patterns and natural sleep preferences increase mental health risk, hinting at the crucial role of sleep timing and chronotype consistency for healthy aging. www.sciencedirect.com
    Sleep Depression Mental Health Anxiety

    The timing of when a person sleeps—not just how long—plays a vital role in mental health, influencing mood, cognitive function, and overall well-being. A recent study found that misalignment between bedtime and natural sleep preferences can increase the risk of mental health disorders like depression and anxiety.

    Researchers identified the chronotype—whether they were morning or evening types—of nearly 74,000 middle-aged and older adults enrolled in the UK Biobank. They tracked sleep patterns using accelerometry and evaluated their sleep and chronotype alignment. They assessed mental health outcomes through standard diagnostic codes.

    They found that morning types who went to bed late had a greater risk of mental health disorders, including depression and anxiety, than those whose sleep timing matched their chronotype. Interestingly, evening types who went to bed early had a lower risk of depression and a trend toward reduced risks of other mental health issues.

    These findings suggest a mismatch between one’s biological preferences and sleep schedule can harm mental well-being. The investigators posited that people should aim to sleep before 1 a.m. for optimal mental health, even if their natural chronotype favors later sleep. Learn more about chronotypes in this clip featuring Dr. Matthew Walker.

    Read more
  • Sleep enhances the brain's waste removal through synchronized fluctuations in norepinephrine and blood volume, a process disrupted by the common sleep aid, zolpidem. https://www.cell.com/cell/abstract/S0092-8674\(24\)01343-6
    Brain Sleep Norepinephrine Neurodegeneration

    The brain doesn’t just rest during sleep—it actively clears out waste that can damage brain cells. This crucial process, known as glymphatic clearance, relies on the movement of cerebrospinal fluid to wash away harmful proteins linked to neurodegenerative diseases. A recent study found that synchronized fluctuations in norepinephrine, blood volume, and cerebrospinal fluid are key drivers of glymphatic clearance during deep sleep, but some popular sleeping pills disrupt this process.

    The researchers tracked blood and cerebrospinal fluid dynamics while mice slept naturally. Then, they examined how zolpidem, commonly known as Ambien, affected these dynamics during sleep.

    They found that norepinephrine fluctuations triggered by the brain’s locus coeruleus drove rhythmic changes in blood vessel size. This facilitated the movement of cerebrospinal fluid into the brain and the removal of waste products. However, zolpidem disrupted norepinephrine activity, reducing cerebrospinal fluid flow and hindering this waste removal process.

    These findings suggest that the brain’s waste removal system relies on a delicate balance of norepinephrine and blood vessel activity. Sleep aids like zolpidem disrupt this process, potentially contributing to neurodegenerative diseases like Alzheimer’s. Learn more about the effects of sleep aids like Ambien in this episode featuring Dr. Matthew Walker.

    Read more
  • Workplace design plays a crucial role in sleep health, with sedentary jobs and nontraditional schedules leading to poor sleep patterns, such as regular insomnia or compensatory 'catch-up' sleep. psycnet.apa.org
    Sleep Circadian Rhythm

    Modern workplace changes driven by technology are transforming not only how we work but also how well we sleep. Longer hours spent at desks, increasing reliance on computers, and nontraditional work schedules may undermine sleep health. A recent study found that modern job designs are linked to distinct sleep challenges among full-time workers.

    Researchers analyzed data from nearly 1,300 adults in the Midlife in the United States study, collected at two points over a decade. They examined six sleep health dimensions, including duration, insomnia symptoms, and daytime tiredness. Then, they identified three sleep health profiles: good sleepers (who had few sleep issues), catch-up sleepers (who relied on naps and non-workday sleep to offset shorter workday sleep), and insomnia sleepers (who experienced short sleep, frequent insomnia symptoms, and daytime tiredness).

    They found that only about half of the participants were good sleepers. Participants with sedentary jobs were more likely to be classified as insomnia sleepers. At the same time, those with nontraditional schedules often exhibited a catch-up sleeper pattern characterized by irregular sleep and regular napping. Good sleepers were less likely to be in these roles, suggesting that workplace design powerfully shapes long-term sleep health.

    These findings suggest that job design has marked effects on sleep quality. Reducing sedentary time and stabilizing work schedules could help workers achieve healthier sleep patterns, ultimately improving well-being and overall health. Learn how shift work and other aspects of modern lifestyles influence sleep and health by altering circadian rhythms in this clip featuring Dr. Satchin Panda.

    Read more
  • Irregular sleep schedules, regardless of sleep duration, are linked to an increased risk of major cardiovascular events. jech.bmj.com
    Sleep Heart Disease Blood Pressure Cardiovascular

    Most people know that sleep quality matters, but few recognize the importance of consistent sleep schedules. Evidence suggests that inconsistent bedtime and wake-up routines could harm heart health. A recent study found that irregular sleep patterns increase the risk of major cardiovascular events, such as heart attacks or strokes, even among people who get enough sleep overall.

    Researchers analyzed data from more than 72,000 adults aged 40 to 79 participating in the UK Biobank study. Participants wore wrist devices for one week to track sleep patterns and regularity. The researchers categorized sleep regularity as irregular, moderately irregular, and regular, and linked these patterns to hospital and death records over eight years to assess the risk of heart attacks, strokes, or heart failure.

    People with irregular sleep schedules were 26% more likely to experience major cardiovascular events than those with regular sleep patterns, while those with moderately irregular sleep had an 8% higher risk. Meeting age-specific sleep duration recommendations helped lower the risk for moderately irregular sleepers but did not fully protect those with highly irregular sleep patterns.

    These findings suggest that maintaining a consistent sleep schedule may be as important as getting enough sleep for cardiovascular health. Learn how to optimize your sleep in this Aliquot featuring Drs. Matt Walker, Satchin Panda, and Rhonda Patrick.

    Read more
  • Whole-body cryotherapy improves mood, reduces anxiety, and enhances sleep quality, with specific enhancement in slow-wave, restorative sleep seen in a recent study. www.sciencedirect.com
    Sleep Mental Health Cold Stress

    Cold exposure offers surprising health benefits, and emerging evidence suggests that whole-body cryotherapy enhances wellness and even improves sleep. A recent study found that five days of daily cryotherapy improved mood, reduced anxiety, and enhanced sleep quality in healthy young adults.

    The study involved 20 physically active young adults who underwent five consecutive days of cryotherapy sessions and five consecutive days of no cold exposure. The cryotherapy sessions lasted five minutes in a chamber cooled to -90°C (-130°F). Researchers used actimetry, brain activity recordings, and self-reported questionnaires to measure the participants' sleep patterns. They also assessed their mood, anxiety, and heart rate variability during the nights following each condition.

    Participants who underwent cryotherapy reported a 9% improvement in subjective sleep quality, with women benefiting the most. The cryotherapy sessions also increased slow-wave sleep, the most restorative sleep phase, by an average of seven minutes per night. No substantial changes were observed in heart rate variability or other sleep parameters.

    These findings from this small study suggest that repeated whole-body cryotherapy is a promising strategy for improving slow-wave sleep and psychological well-being, especially for women. Learn more about cold exposure in our comprehensive overview article.

    Read more
  • Children with earlier bedtimes show up to 40% more diversity in their gut microbiota, potentially indicating better overall health than late sleepers. www.tandfonline.com
    Microbiome Sleep Microbes Development

    Early bedtimes may do more than help children wake up refreshed—they might also shape the balance of bacteria in their guts. A recent study found that children who go to bed early have distinct differences in their gut microbial populations compared to those who stay up later, potentially influencing their metabolism and overall health.

    Researchers collected fecal samples from 88 healthy children between the ages of 2 and 14 and used genetic sequencing to analyze the composition of their gut microbial populations. They compared the diversity of early sleepers' gut bacteria to that of late sleepers, looking for patterns that might relate to sleep timing.

    They found that children with earlier bedtimes had more diverse gut microbial populations, a marker of healthier gut function. Both beta and alpha diversity measures (indicators of the variety and richness of bacteria species) were as much as 40% higher in early sleepers.

    These findings suggest that sleep timing may play a role in shaping gut health. Considering the links between gut health and metabolism, they offer new insights into addressing sleep-related metabolic disorders in children. Learn about the importance of establishing a healthy gut microbiota in early life in this clip featuring Dr. Eran Elinav.

    Read more
  • Exposure to 'forever chemicals,' commonly found in plastics, is linked to 80 minutes less sleep per night and increased sleep disturbances. www.sciencedirect.com
    Sleep Pollution

    Many people find getting a good night’s sleep challenging, and some research suggests that chemicals like per- and poly-fluoroalkyl substances (PFAS), known as “forever chemicals,” could be part of the problem. A recent study found that PFAS exposure is linked to shorter sleep duration and increased sleep disturbances.

    Researchers measured PFAS levels and proteins related to metabolism and inflammation in the blood of 136 healthy young adults. They asked the participants about their sleep duration, sleep disturbances, and sleep-related impairments.

    They found that, on average, those with the highest PFAS levels in their blood slept roughly 80 minutes less per night than those with the lowest levels. Participants with elevated PFAS levels reported more trouble falling and staying asleep, frequent awakenings, and daytime fatigue.

    The researchers also found that specific proteins—11-beta-dehydrogenase isozyme-1 and cathepsin B—might participate in PFAS-driven sleep disruption. 11-beta-dehydrogenase isozyme-1 regulates cortisol, influencing metabolism and stress responses, while cathepsin B breaks down proteins, supporting immune functions such as antigen presentation and inflammation.

    These findings suggest that PFAS exposure disrupts sleep by altering metabolic and immune pathways. PFAS are principal components of plastic, which can break down and enter the environment as microplastics. Consequently, microplastics may be a major contributor to PFAS exposure. Learn more about microplastics and PFAS exposure in this episode featuring Dr. Rhonda Patrick.

    Read more
  • A daily cup of coffee could reduce your risk of heart disease and diabetes by half. academic.oup.com
    Sleep Heart Disease Diabetes Biomarkers Coffee Green Tea Caffeine Stroke Cardiovascular

    Drinking your daily cup of coffee or tea might do more than give you a boost—it could lower your risk of developing multiple serious cardiometabolic conditions simultaneously, like diabetes, heart disease, or stroke. A recent study found that moderate coffee or caffeine consumption may cut your risk of cardiometabolic multimorbidity by as much as 50%.

    Researchers analyzed data from more than 172,000 participants enrolled in the UK Biobank who had no cardiometabolic diseases at the start. Participants reported their coffee, tea, and caffeine consumption; about half provided blood samples for metabolic marker analysis.

    They found that people who drank about three cups of coffee daily (or consumed 200 to 300 milligrams of caffeine daily) were 40% to 50% less likely to develop multiple cardiometabolic diseases than those who drank little or no caffeine. They also discovered that specific blood markers, such as certain lipid components, were linked to coffee and caffeine consumption and a lower risk of cardiometabolic conditions.

    These findings suggest that moderate coffee or caffeine intake reduces the risk of developing cardiometabolic diseases but also slows their progression if they occur. Other evidence points to the many health benefits associated with coffee and caffeine, but it’s crucial to remember their effects on sleep. Learn more in this Aliquot featuring Drs. Guido Kroemer, Satchin Panda, Elissa Epel, Matthew Walker, and Rhonda Patrick

    Read more
  • Frequent nightmares linked to quadruple cognitive decline risk, especially among men. www.thelancet.com
    Aging Sleep Dementia

    Nightmares and bad dreams are common occurrences, with many adults experiencing them monthly. However, a growing body of evidence points to links between nightmares and cognitive function. A recent study found that people who have frequent nightmares have a fourfold greater risk for cognitive decline and dementia.

    The study involved 605 adults enrolled in MIDUS, an ongoing survey of middle-aged and older adults living in the United States. Participants provided information about their sleep quality and distressing dream frequency over about seven years. They also completed cognitive tests and reported whether they had been diagnosed with dementia.

    Middle-aged participants who had weekly distressing dreams were four times more likely to experience cognitive decline during the seven years than those without bad dreams. Older adults with weekly bad dreams were more than twice as likely to experience cognitive decline. The connection between bad dreams and cognitive decline was more robust among men.

    These findings suggest that distressing dreams predict cognitive decline risk, potentially aiding early diagnosis and treatment. Dreams play essential roles in creativity and inspiration. Learn more in this clip featuring Dr. Matthew Walker.

    Read more
  • Caffeine impairs the brain's adaptive response to sleep restriction, reducing gray matter volume. www.nature.com
    Brain Sleep Caffeine

    Nearly three-fourths of adults in the United States don’t get enough sleep, and they often compensate for their sleep losses by consuming caffeine. A recent study found that caffeine and sleep deprivation reduce brain gray matter volume.

    The study involved 36 healthy adults who regularly consumed less than 450 milligrams of caffeine daily—about the amount in four or five cups of coffee. During five days of sleep restriction, 19 participants received 300 milligrams of caffeine in coffee, and 17 received decaffeinated coffee. Researchers analyzed changes in the participants' brains and performed PET scans to measure the availability of the A1 adenosine receptor—a protein involved in sleep regulation—and its relationship to brain plasticity.

    They found that caffeine and sleep restriction synergistically affected brain regions involved in visual processing, decision-making, executive functions, and regulating sensory information, sleep, and consciousness. Participants who had decaffeinated coffee during sleep restriction had more gray matter than those who had caffeinated coffee. Participants with lower baseline adenosine receptor availability generally demonstrated greater gray matter losses.

    These findings suggest an adaptive increase in gray matter volume occurs with sleep restriction, but caffeine impairs this adaptation. Caffeine may have beneficial effects on the body, however, such as boosting autophagy. Learn more in this Aliquot featuring Drs. Guido Kroemer, Satchin Panda, Elissa Epel, Matthew Walker, and Rhonda Patrick.

    Read more
  • Sleep boosts adaptive immune function via the release of hormones that stimulate T-cell migration. www.sciencedirect.com
    Sleep Immune System

    Sleep has profound effects on immune function, driving T-cell migration to lymph nodes – the primary site of adaptive immunity initiation. However, scientists don’t fully understand the mechanisms that underlie links between sleep and immunity. A recent study found that immune-modulating hormones released during sleep mediate T-cell migration.

    The study involved 14 healthy adults with normal sleep patterns. Participants experienced two conditions: 24 hours that included a normal night’s sleep or 24 hours of wakefulness (sleep deprivation). Researchers measured their T-cell numbers, T-cell migration, and hormone levels at various intervals throughout the 24-hour sessions.

    They found that sleep (but not sleep deprivation) increased the spontaneous migration of several T-cell populations toward CCL9, a protein involved in T-cell homing toward lymph nodes. Growth hormone and prolactin (hormones produced in the pituitary gland) mediated these effects. Interestingly, heat exposure induces similar hormonal responses, suggesting that sauna use also bolsters immune function.

    The findings from this small study demonstrate that sleep enhances adaptive immune function by promoting the release of immune-modulating hormones. Learn more about the effects of sleep on immunity in this episode featuring Dr. Roger Seheult.

    Read more
  • Probiotic improves cognition and normalizes circadian rhythms in sleep-deprived mice. www.sciencedirect.com
    Brain Gut Microbiome Sleep Probiotics

    The gut microbiome is crucial for maintaining normal brain processes, and disruptions in gut health can impair cognitive function. Sleep deprivation also impairs cognitive function, but some evidence suggests that probiotics mitigate these effects. A recent study in mice found that probiotics alleviated sleep-deprivation-induced cognitive impairments.

    Researchers fed sleep-deprived mice a probiotic containing Bifidobacterium breve and subjected them to memory and behavioral tests. They also analyzed changes in the animals' gut microbial composition and the presence of crucial microbial metabolites in the gut and serum.

    They found that Bifidobacterium breve improved the sleep-deprived animals' performance in the novel object recognition test – an assessment of recognition memory. The probiotic also altered their gut microbial composition toward a more favorable profile and increased levels of isovaleric acid and gamma-aminobutyric acid (also known as GABA), metabolites involved in melatonin production and circadian rhythm regulation, respectively.

    Bifidobacterium breve is a probiotic bacterium commonly found in the human gut, with particularly large numbers found in young, breastfed infants. It is known for its beneficial effects on digestive health and immune function, and it has been studied for its potential to alleviate various conditions, including gut disorders and Alzheimer’s disease

    These findings suggest that Bifidobacterium breve mitigates sleep-deprivation-induced cognitive impairments and circadian rhythm disturbances in mice. They also highlight a potential role for gut microbial manipulation in treating insomnia and other sleep disorders. Learn more about the relationship between the gut microbiome and sleep in this clip featuring Dr. Matt Walker.

    Read more
  • Gardening improves sleep quality better than other exercises, with sleep problems decreasing as the duration of gardening increases. www.psypost.org
    Exercise Sleep Circadian Rhythm Red Light Therapy

    Gardening is a popular pastime for many people, especially older adults, who benefit from the increased physical activity and mental engagement. A recent study found that people who garden sleep better than those who engage in other exercises or don’t exercise.

    Researchers collected information about the sleep habits of more than 16,000 adults in the U.S. They categorized the participants as gardeners, exercisers, or non-exercisers.

    They found that compared to non-exercisers, gardeners were 42 percent less likely to experience sleep problems, and exercisers were 33 percent less likely. The effects of gardening on sleep were dose-dependent, with sleep problems decreasing as weekly gardening time increased. The benefits of gardening were consistent, even after considering other factors that influence sleep, such as age, sex, education level, and body mass index.

    These findings from this observational study suggest that gardening improves sleep better than other forms of exercise or not exercising. Gardening’s sleep-enhancing effects may stem from increased exposure to natural light during the day, regulating the body’s circadian rhythms and, ultimately, sleep. Learn how light exposure, especially early in the day, influences circadian rhythmicity and sleep in this clip featuring Dr. Satchin Panda.

    Read more
  • Physical activity promotes better sleep – reducing stress and improving mood. medicalxpress.com
    Exercise Sleep Depression Wearable Technology

    Physical activity and sleep are essential for human health, and some evidence suggests they work synergistically to promote mental and physical wellness. A recent study found that physical activity improves aspects of sleep, reducing stress levels and improving mood.

    Researchers used wearable sensors and smartphone tracking to monitor heart rates, sleep, activity levels, and mood in 82 healthy adults over six months. They found that people who engaged in low-, moderate-, or vigorous-intensity exercise tended to have more NREM (deep, slow-wave) sleep and less REM (dream) sleep than non-exercisers. They also tended to enter REM sleep sooner. These changes in sleep patterns correlated with better mood, higher energy levels, less stress, and an enhanced perception of having restful sleep.

    These findings support a growing body of evidence suggesting that physical activity and sleep are intrinsically linked. They also highlight the emerging role of wearable technology as a valuable tool in sleep research.

    Wearable sensors and smartphones allow people to monitor their health, fitness, activity, sleep, or mood. Often simply called “wearables,” these devices can transmit information to a physician, researcher, or user in real time, facilitating data collection and allowing the wearer to actively participate in tracking and maintaining their health. Learn more about wearables in this episode featuring Dr. Michael Snyder.

    Read more
  • A single dose of creatine monohydrate, approximately 20 to 30 grams, depending on body weight, mitigates sleep deprivation's harmful effects on brain function and cognition. www.nature.com
    Brain Diet Sleep Supplements

    Sleep deprivation profoundly affects the human body, negatively influencing cognitive performance, cardiovascular health, and metabolism. Evidence suggests creatine counters some of the harmful effects of sleep deprivation. A recent study found that a single dose of creatine monohydrate improved cognitive performance and prevented harmful metabolic effects in sleep-deprived people.

    The study involved 15 healthy participants who received a single large dose of creatine monohydrate (0.35 grams per kilogram of body weight) or a placebo to assess creatine’s effects on cognitive function during prolonged wakefulness. Participants underwent evaluations before and several hours after taking their respective treatments in the context of 21 hours of sleep deprivation. They underwent brain imaging scans and cognitive tests to measure the effects of creatine on brain chemistry and cognitive performance.

    The scans and tests revealed that creatine induced several critical changes in the brain, including:

    Increasing the ratio of phosphocreatine to inorganic phosphate, providing more energy for brain cells.

    Boosting the levels of ATP, supporting better brain activity and energy management.

    Altering the ratio of creatine to N-acetylaspartate, enhancing brain cell health and boosting energy reserves.

    Maintaining optimal brain pH levels, supporting brain function and neurotransmitter signaling.

    Enhancing cognitive performance and processing speed, making thinking and processing information faster and more efficient.

    These findings suggest that a large dose of creatine could mitigate some of the harmful effects of sleep deprivation on the brain and cognitive function. Creatine is a nitrogen-containing compound produced in the liver and kidneys and stored in the brain and muscles. It plays an essential role in the recycling of ATP and is widely used as a dietary supplement to build and maintain muscle mass. Although creatine is available in many forms, the bulk of the research on the compound has centered on creatine monohydrate. Learn more about creatine in this clip featuring Dr. Stuart Phillips.

    Read more
  • Adopting three or more healthy lifestyle behaviors, including no smoking, optimal sleep, and vigorous physical activity, decreases the risk of irritable bowel syndrome by 42 percent. www.theguardian.com
    Exercise Gut Diet Sleep Inflammation Alcohol Tobacco

    Irritable bowel syndrome (IBS) is a digestive disorder characterized by abdominal cramping, gas, diarrhea, and constipation. The condition affects as many as 10 percent of people worldwide and has no cure. A recent study shows that adopting three or more healthy lifestyle behaviors may reduce the risk of IBS by as much as 42 percent.

    The study involved more than 64,000 people enrolled in the UK Biobank database. Researchers collected information about the participants' dietary intake and whether they engaged in any of five healthy lifestyle behaviors: never smoking, getting optimal sleep, engaging in vigorous physical activity, eating a quality diet, and moderating their alcohol intake.

    They found that 11.8 percent of the participants did not practice any of the five critical healthy behaviors; 32.1 percent practiced one, 34.1 percent practiced two, and 21.9 percent practiced three to five healthy behaviors. As participants engaged in more healthy behaviors, their likelihood of developing IBS decreased, with those practicing one healthy behavior having a 21 percent lower risk, those with two healthy behaviors having a 36 percent lower risk, and those engaging in three to five healthy behaviors having a 42 percent lower risk. These findings were consistent across various groups, regardless of age, sex, job status, where they lived, history of gastrointestinal infection, endometriosis, family history of IBS, or other lifestyle habits.

    These findings suggest that adopting multiple healthy lifestyle behaviors, such as not smoking, staying physically active, and getting good sleep, can significantly reduce the risk of developing IBS. Learn more about factors that influence gut health in this episode featuring Dr. Eran Elinav.

    Read more
  • Having a late chronotype increases coronary artery calcification risk by 90 percent. www.sciencedirect.com
    Sleep Cardiovascular

    A person’s chronotype – their innate tendency to sleep at a particular time during a 24-hour period – is based on genetically determined circadian rhythms. Disruption of a person’s chronotype schedule can influence mood, productivity, and disease risk. A recent study shows that having a late chronotype increases a person’s risk of coronary artery calcification, a marker of atherosclerosis.

    Researchers assessed the extent of coronary artery calcification in 771 middle-aged adults using computer tomography (CT). They monitored the participants' physical activity levels and asked them to identify their chronotype: extreme morning, moderate morning, intermediate, moderate evening, or extreme evening.

    They found that extreme evening chronotypes were 90 percent more likely to have coronary artery calcification than extreme morning types. In addition, the later a participant’s chronotype, the greater their coronary artery calcification, roughly doubling from 22 percent for extreme morning types to 41 percent for extreme evening types.

    These findings suggest that chronotype influences a person’s risk for atherosclerosis. They also align with other research showing that people with evening chronotypes are at greater risk for cardiovascular disease and premature death than morning types. Learn more about chronotypes and their effects on human health in this clip featuring Dr. Matthew Walker.

    Read more
  • Deep sleep supports cardiovascular health by boosting left ventricular function. www.sciencedaily.com
    Brain Sleep Heart Disease

    Deep sleep, characterized by slow brain waves, heart rate, and respiration, is essential for memory formation and immune function. Evidence suggests deep sleep influences cardiovascular health, too. A recent study found that deep sleep enhances left ventricular function – how well the heart’s left ventricle pumps blood throughout the body with each heartbeat.

    Researchers recruited 18 healthy adult males to participate in a sleep study. They measured their brain and heart activity, blood pressure, and carotid pulse-wave velocity (a measure of arterial stiffness). When the participants reached deep sleep, the researchers exposed them to short bursts of pink noise (white noise with the high frequencies filtered out).

    They found that the pink noise enhanced the participants' slow-wave brain activity. Interestingly, it also improved their left ventricular function, as indicated by enhanced pumping and filling capacities. Exposure to pink noise increased systolic blood pressure slightly but did not influence arterial stiffness.

    Sleep occurs in distinct stages, the most prominent of which is non-rapid eye movement (NREM) sleep – typically referred to as “deep sleep” or “slow-wave sleep.” It comprises approximately 75 to 80 percent of a person’s total sleep time. During NREM sleep, the body produces growth hormone, which plays a role in metabolism.

    The findings from this small study suggest that pink noise promotes deep sleep, driving improvements in cardiovascular function. Other evidence suggests that deep sleep provides a homeostatic recalibration of blood pressure, further supporting cardiovascular health. Learn more in this clip featuring Dr. Matthew Walker.

    Read more
  • Jet lag causes rats to overeat, linking circadian rhythm disruption to altered appetite regulation and weight gain. www.sciencedaily.com
    Obesity Sleep Hormones Circadian Rhythm

    Circadian rhythms regulate the body’s many physiological processes, including those influencing appetite. Disrupted rhythms, such as those occurring with shift work or jet lag, can alter appetite, contributing to weight gain. A recent study showed that rats with jet lag ate 460 percent more food during their resting phase than non-jet-lagged rats.

    Researchers studied two groups of rats: one that experienced typical light/dark cues (a control group) and one that experienced reversed cues (a “jet-lagged” group) for five days. They monitored the animals' food intake and measured levels of glucocorticoids, a class of hormones that regulate behavior, sleep-wake cycles, and metabolism.

    They found that jet-lagged animals demonstrated dysregulated orexigenic hypothalamic neuropeptide, a glucocorticoid hormone that regulates appetite. This dysregulation increased their desire to eat during their inactive phase (when they typically rest), consuming 460 percent more food than the control group. The overeating rats didn’t gain weight during the study period, likely due to the short duration.

    These findings suggest that circadian rhythm disruption alters glucocorticoid levels in rats, driving increased food consumption. Although the animals didn’t gain weight during the study, longer disruption (as in shift work) may drive considerable weight gain. The study’s authors posited that maintaining a consistent daily schedule and regular meals may help mitigate the effects of circadian rhythm disruption. Learn more about how shift work and jet lag influence circadian rhythms in this clip featuring Dr. Satchin Panda.

    Read more
  • High-intensity exercise mitigates sleep-induced metabolic disruptions, offering a potential defense against type 2 diabetes. www.sciencedirect.com
    Exercise Metabolism Sleep Diabetes Circadian Rhythm Mitochondria

    Poor sleep negatively affects metabolism, impairing glucose tolerance and increasing the risk of developing type 2 diabetes. Findings from a recent study indicate that HIIT compensates for the harmful effects of sleep loss on glucose tolerance.

    Researchers assigned 24 healthy young men to one of three five-night sleep protocols: normal sleep (eight hours nightly), sleep restriction (four hours nightly), and sleep restriction with HIIT. Researchers collected muscle biopsies to assess muscle protein synthesis before and after the intervention.

    They found that the group with sleep restriction experienced marked reductions in glucose tolerance, mitochondrial respiratory function, and sarcoplasmic protein synthesis. They also experienced altered diurnal skin temperature rhythms. However, sleep-restricted participants who engaged in HIIT did not experience these disturbances.

    The sarcoplasm is the cytoplasm of muscle cells. Sarcoplasmic protein synthesis is crucial for muscle growth, repair, and maintenance, contributing to overall muscle health and function.

    This study was small, but the findings suggest that sleep restriction impairs metabolic function, circadian rhythmicity, and muscle protein synthesis. However, engaging in HIIT during periods of sleep restriction helps counter these effects. Learn more about the benefits of HIIT in this episode featuring Dr. Martin Gibala.

    Read more
  • High-intensity interval training counteracts muscle protein loss induced by sleep deprivation. www.ncbi.nlm.nih.gov
    Exercise Sleep Muscle Protein Aerobic

    Sleep deprivation profoundly affects the human body, negatively influencing cognitive performance, cardiovascular health, and more. Findings from a 2020 study suggest that sleep deprivation impairs muscle protein synthesis, but exercise counters this effect. People who slept only four hours per night but engaged in high-intensity interval training (HIIT) exhibited muscle protein synthesis comparable to those who slept a full night.

    Researchers assigned 24 healthy young men to one of three five-night sleep protocols: normal sleep (eight hours nightly), sleep restriction (four hours nightly), and sleep restriction with HIIT. Researchers collected muscle biopsies to assess muscle protein synthesis before and after the intervention.

    They found that the group with sleep restriction had lower rates of muscle protein synthesis than those with normal sleep and those who combined sleep restriction with HIIT.

    HIIT is a time-efficient strategy to promote cardiovascular fitness and metabolic health. Its flexibility accommodates a wide range of exercises, including walking, running, cycling, and even resistance training, making it accessible to people of different fitness levels and abilities.

    This was a small study, but the findings suggest that sleep restriction reduces muscle protein synthesis, potentially contributing to muscle loss. However, engaging in HIIT during periods of sleep restriction helps maintain muscle protein synthesis, potentially counteracting the adverse effects of sleep loss on muscle mass. Learn more about the benefits of HIIT in this episode featuring Dr. Martin Gibala

    Former FMF guest Dr. Stuart Phillips was a collaborator and participant in this study. Learn more about Dr. Phillips' research in this episode.

    Read more
  • Sleep deprivation leads to fatal accumulation of oxidative stress in the gut, but antioxidant diet can extend lifespan. www.genengnews.com
    Gut Sleep Antioxidant Oxidative Stress

    Sleep – a state that renders animals stationary and less responsive to stimuli – is crucial for survival. Some evidence suggests that sleep is important because it protects the body against harmful oxidative stress. A 2020 study in flies and mice showed that reactive oxygen species, which drive oxidative stress, accumulate in the gut during sleep deprivation, leading to death.

    Researchers deprived flies and mice of sleep for various durations, occasionally allowing them to sleep. Then, they measured reactive oxygen species in the animals' tissues, including the heart, brain, muscles, and gut. They repeated the experiment but gave the animals antioxidant compounds during the sleep deprivation period.

    They found that animals that experienced extended sleep deprivation died, but allowing them to sleep periodically prevented death, albeit with slightly shorter lifespans. Sleep deprivation markedly increased reactive oxygen species in the animals' guts. After ending the sleep deprivation, the reactive oxygen species levels slowly decreased, nearly returning to their baseline levels. Providing the animals with dietary antioxidant compounds reduced the harmful effects of reactive oxygen species, and the animals lived normal lifespans despite sleep deprivation.

    These findings suggest that sleep deprivation shortens lifespan and causes death due to the accumulation of reactive species in the guts of flies and mice. However, dietary antioxidant compounds reduce reactive oxygen species in the gut and moderate the harmful effects of sleep deprivation. Learn how sleep deprivation affects the brain in this short video featuring Dr. Rhonda Patrick.

    Read more
  • Untreated sleep apnea may impair men's social cognition – the ability to understand and recognize social cues and emotions. www.sciencealert.com
    Brain Aging Sleep

    Untreated sleep apnea may harm the brain, a new study shows. Middle-aged men with sleep apnea performed worse on tests of cognitive and social function than healthy men.

    Researchers compared 27 middle-aged men who had either mild or severe untreated sleep apnea with seven healthy men. Each of the men underwent a sleep study and apnea assessment and took a battery of neuropsychological tests.

    The researchers found that the men with sleep apnea had worse cognitive function, including poorer attention, memory, and decision-making capabilities, compared to the healthy men. They also found that sleep apnea impaired the men’s social cognition – the ability to understand and recognize social cues and emotions. Social cognition can be impaired in certain mental health conditions, such as depression, and may be connected to sleep patterns.

    Sleep apnea is a common, but serious, sleep disorder characterized by brief moments of paused or shallow breathing. People with sleep apnea are at greater risk of high blood pressure, stroke, abnormal heart rhythms, heart failure, diabetes, weight gain, and heart attacks.

    The findings from this small study suggest that sleep apnea impairs cognitive function as early as middle age in men. Larger studies that also include women are needed to confirm the role that sleep apnea plays in cognitive decline. Learn about the role that sleep plays in preventing dementia in this short video featuring Dr. Rhonda Patrick.

    Read more
  • Connection identified between sleep disturbances and stroke risk. www.medscape.com
    Sleep Stroke Cardiovascular

    Sleep disturbances may increase a person’s risk of stroke, according to a new study. People who had trouble falling or staying asleep, snored, or had sleep apnea were more likely to have a stroke than those with normal sleep patterns.

    Researchers gathered information about the sleep patterns of more than 4,500 adults. Roughly half of the participants had experienced a recent stroke.

    They found that compared to participants who slept seven hours a night, those who slept fewer than five hours per night were more than three times as likely to have had a stroke, and those who slept more than nine hours were more than twice as likely to have had a stroke. Participants who had symptoms of apnea were roughly three times as likely to have had a stroke.

    These findings suggest that disturbed sleep markedly increases a person’s risk of stroke. However, the researchers noted that it’s not clear whether sleep disturbances directly cause stroke, or if they are simply markers of other underlying health issues that increase the risk of stroke. Learn more about the health risks associated with poor sleep in this episode featuring Dr. Matthew Walker.

    Read more
  • Increasing activity levels improves sleep quality in women. neurosciencenews.com
    Exercise Sleep

    A new study shows that replacing sedentary time with physical activity improves sleep in women. Women who swapped just one hour of sedentary time or low-intensity activity with moderate- or vigorous-intensity activity slept better and felt more rested.

    Researchers investigated the effects of replacing sedentary time with physical activity. The study involved 683 men and women between the ages of 40 and 64 years. The participants wore accelerometers to gauge their activity levels for one week and reported their sleep quality.

    The researchers found that sleep measures improved when women replaced sedentary behavior or low-intensity physical activity with moderate- to vigorous-intensity physical activity. Interestingly, they found no associations between altering men’s activity levels and sleep quality, highlighting the sex-related differences in response to exercise.

    These findings indicate that engaging in moderate- to vigorous-intensity physical activity improves sleep quality in middle-aged women. They also align with other studies that show that exercise improves sleep. Sleep is essential for human health. Learn more about the benefits of sleep in this episode featuring Dr. Matthew Walker.

    Read more
  • Intake of sulforaphane precursor may improve sleep quality. www.sciencedirect.com
    Diet Sleep Sulforaphane Glucoraphanin

    A compound present in broccoli sprouts may help you sleep better at night, a new study shows. People who consumed glucoraphanin – a bioactive compound found in broccoli sprouts that is a precursor to sulforaphane – slept better and had lower inflammatory markers than those who didn’t take the compound.

    Researchers conducted a small, randomized, placebo-controlled trial involving 18 healthy adults. Twelve of the participants took 30 milligrams of glucoraphanin daily for four weeks while the remaining six took a placebo. The participants wore sleep monitors and reported their sleep quality. The researchers measured the participants' melatonin and inflammatory markers.

    They found that the participants who took the glucoraphanin experienced better sleep quality than those who took the placebo. They also had higher blood concentrations of melatonin and lower levels of prostaglandin D2, a pro-inflammatory mediator.

    Melatonin is a hormone produced deep within the brain, in the pineal gland. It is a key player in the body’s circadian metabolic processes and serves as the body’s natural sleep inducer. Melatonin production may be impaired in a pro-inflammatory state, and increased oxidative stress and inflammation may reduce sleep quality.

    Glucoraphanin is found in certain cruciferous vegetables, including broccoli (especially broccoli sprouts) and red kale. Glucoraphanin is hydrolyzed by the enzyme myrosinase to produce sulforaphane, which demonstrates many beneficial effects in humans. Learn more about the health effects of sulforaphane in this live Q&A featuring Dr. Jed Fahey.

    Read more
  • Doubling of estrogen and progesterone levels was associated with lower odds of snoring (-19%) and symptoms of sleep apnea (-23%) in women. (2022) www.sciencedaily.com
    Sleep Hormones Estrogen

    From the article:

    In the new study, the researchers analyzed data from 774 women aged 40 to 67 in the European Community Respiratory Health Survey, conducted in seven countries between 2010 and 2012. Women in the study participated in questionnaires on their respiratory health, women’s health factors, lifestyle and sleep, and gave blood samples for hormone analysis.

    551 of the women in the study (71.2%) had been told they snored, and 411 of those women also reported other symptoms of sleep apnea. Among all women, a doubling of serum concentrations of estrone was associated with 19% decreased odds of snoring. A doubling of progesterone levels was associated with 9% decreased odds of snoring. Among snorers, a doubling of the concentrations of three estrogens (17β-estradiol, estrone and estrone 3-sulfate) was associated with 17% to 23% decreased odds of women having been told they breathe irregularly during sleep. A doubling of progesterone concentration, among snorers, was associated with 12% decreased odds of having woken with a choking sensation in the previous year.

    View full publication

    Read more
  • Sleep loss and lower sleep duration may be associated with lower morning, afternoon and 24-h testosterone levels. (2022) link.springer.com
    Sleep Hormones Insulin Resistance Cortisol Testosterone

    From the publication:

    When epidemiological and interventional studies are considered collectively, sleep loss and lower sleep duration are associated with lower morning, afternoon and 24-h testosterone; as well as higher afternoon, but not morning or 24-h cortisol. These reciprocal changes imbalances anabolic-catabolic signaling because testosterone and cortisol are respectively the main anabolic and catabolic signals in man. Fixing testosterone-cortisol balance by means of a novel dual-hormone clamp mitigates the induction of insulin resistance by sleep restriction and provided the first proof-of-concept that the metabolic harm from sleep loss can be ameliorated by approaches that do not require sleeping more. Obstructive sleep apnea is associated with lower testosterone, even after controlling for age and obesity whereas the conclusion that continuous positive airway pressure therapy has no effect on testosterone is premature because available studies are underpowered and better-quality studies suggest otherwise. High dose testosterone therapy induces OSA [obstructive sleep apnea], but more physiological dosing may not; and this effect may be transient or may dissipate with longer term therapy.

    Read more
  • Several environmental and lifestyle factors can lower testosterone levels. (2020) www.tandfonline.com
    Vitamin D Diet Obesity Sleep Hormones Stress Magnesium Testosterone Zinc Polyphenol Oxidative Stress

    From the publication:

    Many factors, including external, environmental and internal factors, influence testosterone levels. The impact of energy intake derived from a testosterone-boosting diet depends on a human body mass. In the case of people of healthy body mass, insufficient energy intake may result in a reduction in testosterone levels in men. The same energy deficit in obese people, may, in turn, result in a neutral or positive impact on the levels of the hormone. Undoubtedly, nutritional deficiency, and particularly of such nutrients as zinc, magnesium, vitamin D, together with low polyphenols intake, affects the HPG [hypothalamic–pituitary–gonadal] axis. The levels of mental and oxidative stress can also adversely impact the axis. The higher the cortisol levels in a human body, or the higher its daily fluctuation, the lower the testosterone levels. What is more, the effect seems to be strengthened by excessive body weight, which is related to the increased oxidative stress affecting the functions of the Leydig cells. Other factors which might disrupt testosterone synthesis may be the length and quality of sleep. Even though the issue is relatively unknown, it appears that both sleep deprivation (shorter than five hours) and low quality of sleep (sleeping with the light on, sleeping during the day, under the influence of alcohol) impact the testosterone levels negatively.

    Read more
  • Testosterone therapy may play a small role in temporarily exacerbating or inducing changes in obstructive sleep apnea. (2021) www.sciencedirect.com
    Obesity Sleep Hormones Testosterone Weight Loss

    From the publication:

    The best current evidence suggests that short-term, high-dose testosterone administration mildly worsens OSA [obstructive sleep apnea]. Longer-term TTh [testosterone therapy] in subjects undergoing concomitant weight loss was shown to mildly worsen OSA but only initially. By 18 weeks, patients demonstrated return to baseline levels of OSA risk. These results suggest that TTh’s role in exacerbating OSA is small and may be time limited. However, it is also possible that weight loss acted as a confounding factor. Additional studies are needed to determine if men who are more obese at baseline have a higher risk of developing OSA with TTh than nonobese men. Why testosterone would have a timedependent effect, however, remains unanswered. Regarding the mechanisms by which TTh may worsen OSA, anatomic TTh-induced airway changes and altered sleep stage architecture have been largely refuted. The mechanism of action is more likely related to altered hypoxic and hypercapnic ventilatory response with testosterone administration, though work is still needed to resolve inconsistencies in currently available studies. Until these questions are more fully understood, clinicians may choose to exercise caution in prescribing TTh to individuals with severe, untreated OSA.

    Read more
  • Obstructive sleep apnea may have a suppressive effect on serum testosterone levels in men, independent of BMI and age. (2021) onlinelibrary.wiley.com
    Obesity Sleep Hormones Testosterone

    Sleep apnea increases the risk of low testosterone.

    Men with sleep apnea are more likely to have low testosterone levels, according to a 2021 study. Men with severe apnea are at the greatest risk of low testosterone.

    Researchers reviewed the findings of 18 studies involving more than 1,800 men that examined links between sleep apnea and male testosterone levels. Then they analyzed a subset of the studies after matching the men’s age, body mass index, and severity of their sleep apnea.

    They found that the men with sleep apnea were more likely to have low testosterone levels, even after considering their age and body mass index. However, the subset analysis revealed that this relationship was only notable for those with severe apnea.

    Sleep apnea is a common, but serious, sleep disorder characterized by brief moments of paused or shallow breathing. People with sleep apnea are at greater risk of high blood pressure, stroke, abnormal heart rhythms, heart failure, diabetes, weight gain, and heart attacks.

    This review identifies links between sleep apnea and testosterone levels. It also underscores the importance of diagnosing and treating sleep apnea, particularly among men whose apnea is more severe.

    Read more
  • Improving sleep, diet, fitness, and weight may be alternatives to testosterone therapy. (2018) www.sciencedirect.com
    Exercise Diet Sleep Hormones Stress Meditation Testosterone Weight Loss

    From the publication:

    Patient interest in fertility and testicular size preservation and a desire to avoid lifelong medical therapy with testosterone drives the need to identify non-TTh [non-testosterone therapy] for hypogonadism. Medical therapies that can stimulate endogenous testosterone production include hCG [human chorionic gonadotropin], AIs [aromatase inhibitors], and SERMs [selective estrogen receptor modulators], all of which demonstrate efficacy in increasing serum testosterone levels and good safety profiles. Natural therapies to increase testosterone production include diet and exercise, weight loss, improved sleep, decreasing stress, and varicocele repair. Diet, exercise, and weight loss provide a means to potentially reverse comorbidities that are closely linked to hypogonadism. Improvements in sleep quality and duration and decreasing stress are additional lifestyle modifications that can improve testosterone levels without the need for lifelong medication. Varicocele repair also can increase testosterone levels, although rigorous data supporting its use remain lacking. Patients considering TTh should be counseled on disease modification and the possibility of discontinuing TTh in the future, before initiation of therapy, and the alternatives discussed in this review also should be considered first in appropriate candidates.

    […]

    Diet, exercise, and weight loss

    – 12-wk lifestyle modification program involving aerobic exercise and diet modification significantly increased mean testosterone levels

    – 52-wk program of diet and exercise significantly increased mean serum testosterone levels

    – Individuals who lost 10% of weight between visits showed a significant increase in testosterone levels

    – Weight loss through low-calorie diets or bariatric surgery was associated with significant increases in total testosterone levels

    Improvements in sleep

    – Men with OSA treated with UPPP had significant 3-mo postoperative increases in testosterone levels

    – Restriction of sleep to 5 h/night decreased testosterone levels by 10-15%

    Stress reduction

    – Men with high stress levels had significantly lower serum testosterone levels compared with controls

    – Men with higher work stress had higher than expected incidence of hypogonadism

    Varicocele repair

    – Varicocelectomy significantly increased mean testosterone levels

    – Varicocele repair significantly increased testosterone levels

    – Significantly increased total testosterone levels were found at 12-mo follow-up after varicocelectomy

    – Mean serum total testosterone significantly increased after varicocelectomy

    Read more
  • In overweight and obese men, higher testosterone levels may be associated with poorer sleep quality. (2014) www.sciencedaily.com
    Obesity Sleep Hormones Testosterone

    From the publication:

    The research team performed a polysomnogram, or overnight sleep study, in 44 men ages 20 to 50 years who were overweight or obese. All subjects were otherwise healthy and were nonsmokers. Their selection for the study did not consider whether they had symptoms or a history of sleep apnea, according to Van Cauter. However, the sleep study showed that 29 (66 percent) of the men did have OSA [obstructive sleep apnea], which she said was moderately severe in most cases.

    […]

    Later analyses demonstrated that higher total testosterone level strongly correlated with more shallow sleep. This association, Van Cauter said, was independent from the presence of other factors known to decrease sleep quality, such as age, race/ethnicity and OSA [obstructive sleep apnea] severity.

    View full publication

    Read more
  • Sleep quantity may affect morning testosterone levels in older men. (2007) www.sciencedaily.com
    Sleep Hormones Testosterone

    From the publication:

    The study, conducted by Plamen Penev, MD, PhD, of the University of Chicago, focused on 12 healthy men between the ages of 64 and 74. Three morning blood samples were pooled for the measurement of total and free testosterone. In addition to overnight laboratory polysomnography, wrist activity monitoring for six-to-nine days were used to determine the amount of nighttime sleep of the participants in everyday life settings.

    The main outcome levels were total sleep time and morning testosterone levels. Analyses revealed that the amount of nighttime sleep measured by polysomnography was an independent predictor of the subjects' morning total and free testosterone levels.

    “The results of the study raise the possibility that older men who obtain less actual sleep during the night have lower blood testosterone levels in the morning,” said Penev. “Although the findings suggest that how long a person sleeps may be an indicator of age-related changes in important hormone signals in the body, future studies are needed to determine the importance of these relationships for the health of older adults.”

    View full publication

    Read more
  • Chronic poor sleep activates the immune system and promotes inflammation. rupress.org
    Sleep Inflammation Immune System

    A new study shows that chronic poor sleep increases immune cell numbers and promotes inflammation, but good, consistent sleep helps maintain a healthy balance of white blood cells and supports normal immune function.

    The study involved 14 healthy adults who experienced two six-week sleep protocols – one in which they got sufficient sleep (about 7.5 hours) every night and one in which they got about 6 hours of sleep every night – separated by a six-week break. The investigators measured inflammatory markers in the participants' blood every morning and afternoon of the last two weeks of each protocol.

    They found that when the participants didn’t get enough sleep, their afternoon blood samples had higher levels of immune cells called monocytes and markers of immune activation compared to when they got enough sleep. Poor sleep also induced epigenetic changes in stem cells that produce immune cells, reducing their progeny’s diversity and tipping the balance of immune cell production toward an inflammatory profile.

    Sleep has profound effects on human health. Not getting enough sleep or having poor, fragmented sleep drives an increase in the production of myeloid cells, a type of white blood cell that predominates in aging and activates inflammasomes – drivers of inflammation.

    These findings suggest that sleep preserves healthy immune cell production, thereby reducing inflammation. Learn more about the health benefits of sleep in this episode featuring Dr. Matthew Walker.

    Read more
  • Sleeping only five hours decreased testosterone levels by 10 to 15% in young healthy men. (2011) www.sciencedaily.com
    Sleep Hormones Mental Health Testosterone

    Sleep deprivation reduces testosterone levels in young men.

    Just one week of sleep deprivation reduces young men’s testosterone levels by as much as 15 percent, according to a 2011 study. Missing out on sleep worsened the young men’s mood and overall energy levels, too.

    In the study, 10 young, healthy, college-age men got a good night’s sleep for three nights, and then they got just five hours per night for eight nights. Researchers monitored their sleep and collected blood samples from the men every 15 to 30 minutes throughout the last day of each sleep protocol.

    They found that getting five hours of sleep a night for just one week drastically reduced the men’s testosterone levels – by as much as 10 to 15 percent. Testosterone levels began to plummet in the afternoons and continued to drop until late at night. The men also experienced marked reductions in their overall energy levels and moods.

    Roughly one-third of working adults in the United States get fewer than six hours of sleep every night – a problem linked with a variety of acute and chronic health conditions, including an increased risk of colds, high blood pressure, diabetes, heart attack, heart failure, and stroke. Evidence suggests that poor sleep reduces sex drive.

    The findings from this study suggest that getting even a few nights of poor sleep alters testosterone, energy levels, and mood in young, healthy men. Learn about other effects of sleep deprivation in this clip featuring Dr. Matthew Walker.

    Read more
  • In a study of men with low testosterone, 56% of study participants suffered from depression or showed depressive symptoms. (2015) www.sciencedaily.com
    Obesity Sleep Hormones Depression Mental Health Sex Testosterone

    From the article:

    The research, slated to publish online on July 1 in the Journal of Sexual Medicine, involved 200 adult men, aged 20-77, with a mean age of 48 years old, who were referred for borderline total testosterone levels between 200 and 350 ng/dL. Information gathered included demographics, medical histories, medication use, signs and symptoms of hypogonadism, and assessments of depressive symptoms and/or a known diagnosis of depression or use of an antidepressant.

    Depression and/or depressive symptoms were present in 56 percent of the subjects. Furthermore, one quarter of the men in the study were taking antidepressants and that the men had high rates of obesity and low rates of physical activity. The most common symptoms were erectile dysfunction, decreased libido, fewer morning erections, low energy, and sleep disturbances.

    View full publication

    Read more
  • Even moderate light exposure during sleep harms heart health and increases insulin resistance www.sciencedaily.com
    Sleep Insulin Resistance

    A single night of light exposure during sleep impairs glucose metabolism via activation of the “fight-or-flight” response.

    Light is the primary signal that entrains the body’s master clock to set its 24-hour circadian cycle. Consequently, the body is synchronized to external light-dark cycles. In recent decades, exposure to light from artificial sources has increased, especially during the evening and nighttime hours, with negative effects on human health. Findings from a recent study suggest that a single night of light exposure impairs glucose metabolism via activation of the sympathetic nervous system.

    The sympathetic nervous system is a division of the autonomic nervous system. It responds to both endogenous and exogenous stressors and is widely referred to as the coordinator of the body’s “fight-or-flight” response. The outcome of sympathetic nervous system activation is an increase in heart rate, cardiac output, and blood glucose levels, as well as other physiological responses that prepare the body for action. Evidence suggests that increased sympathetic nervous system activity alters sympathovagal balance (the balance between the sympathetic and parasympathetic nervous systems), driving poor heart rate variability.

    The investigators recruited 20 healthy adults (average age, 26 years) who did not have sleep disorders. Participants spent two nights in a sleep laboratory, where they ate all their meals and went to bed at their habitual times. Half of the participants spent one night in dim light conditions (less than 3 lux, very dark) and one night in room light conditions (100 lux, from four 60-watt incandescent bulbs). The other half spent both nights in the dim light conditions. Participants provided blood samples and underwent oral glucose tolerance tests each morning.

    The investigators found that participants who were exposed to room light conditions during sleep had increased nighttime heart rate, decreased heart rate variability, and increased morning insulin resistance, compared to when they slept in a dark room. They also spent less time in deep, slow-wave sleep.

    These findings suggest that a single night of exposure to room light during sleep impairs glucose metabolism via activation of the sympathetic nervous system. Learn how light from devices impairs sleep in this clip featuring sleep expert Dr. Matthew Walker.

    Read more
  • People Who Sleep Less Than Seven Hours Show Lower Intakes of Micro- and Macronutrients www.sci-news.com
    Nutrition Sleep

    People who don’t get enough macro- or micronutrients or fiber have poor sleep.

    Macronutrients (carbohydrates, fats, and proteins), micronutrients (vitamins and minerals), and fiber are the core components of the diet. Inadequate intake of these nutrients can impair biological processes and cause both acute and chronic health problems. Findings from a 2019 study suggest that people who don’t get enough macro- or micronutrients or fiber have poor sleep.

    Sleep is essential for human health. Not getting enough sleep or having poor, fragmented sleep increases a person’s risk of developing many chronic illnesses, including cardiovascular disease, hypertension, diabetes, stroke, obesity, and depression. Evidence suggests that insufficient sleep increases a person’s risk of developing Alzheimer’s disease and dementia. The investigators analyzed data collected in the National Health and Nutrition Examination Survey, an ongoing study of the health and nutritional status of people living in the United States. Their analysis included adults who provided information about their dietary intake, sleep patterns, and overall health.

    They found that roughly one-third of the participants reported short sleep (regularly sleeping less than seven hours per night) and nearly one-half reported having poor sleep quality. Those who had short sleep or poor sleep quality were more likely to have a lower intake of several macro- and micronutrients, including magnesium, niacin, zinc, vitamins A, K, B1, B6, and B12, calcium, and dietary fiber. Although the effects were stronger in women, dietary supplements compensated for the low dietary intake.

    These findings suggest that low intake of macro- and micronutrients impairs sleep in adults and suggest that dietary supplements can compensate for dietary shortcomings. Learn about other dietary components that influence sleep duration and quality in this clip featuring Dr. Matthew Walker.

    Read more
  • Children who lack sleep may experience detrimental impact on brain and cognitive development that persists over time www.eurekalert.org
    Brain Sleep

    Children who don’t get enough sleep have altered brain structure and impaired brain function.

    Sleep is essential for normal brain development in children. The American Academy of Pediatrics recommends that children between the ages of six and 12 years sleep nine to 12 hours every night for optimal health, but many children do not meet these recommendations. Findings from a recent study suggest that children who don’t get enough sleep have altered brain structure and impaired brain function.

    The investigators analyzed structural magnetic resonance imaging data and medical records for more than 8,300 children between the ages of nine and ten years who were enrolled in the Adolescent Brain Cognitive Development (ABCD) Study. They also assessed the children’s cognitive performance and mental health status. The parents of the children in the study provided information about their child’s nightly sleep duration. Assessments were repeated when the children reached the ages of 11 to 12 years.

    The study revealed that brain volumes in areas responsible for attention, memory, and inhibition were lower in sleep-deprived children than in those who received adequate sleep. In addition, children who had shorter sleep duration were more likely to experience depression and anxiety and exhibit impulsive behavior and poor cognitive performance. The association between poor sleep and depression persisted at the two-year follow-up.

    These findings underscore the importance of adequate sleep for proper brain function, especially in the developing brain. Learn more about the importance of sleep in this episode featuring Dr. Matthew Walker.

    Read more
  • Insomnia, hypertension and smoking, but not high triglyceride levels, are considered possible risk factors for brain aneurysm rupture. www.sciencedaily.com
    Sleep Genetics Tobacco Triglycerides Blood Pressure Aneurysm

    From the article:

    Data from several genome-wide association studies were used to gauge genetic associations to lifestyle and cardiometabolic risk factors. […] According to the analysis:

    -A genetic predisposition for insomnia was associated with a 24% increased risk for intracranial aneurysm and aneurysmal subarachnoid hemorrhage.

    -The risk for intracranial aneurysm was about three times higher for smokers vs. non-smokers.

    -The risk for intracranial aneurysm was almost three times higher for each 10 mm Hg increase in diastolic blood pressure (the bottom number in a blood pressure reading).

    -High triglyceride levels and high BMI did not demonstrate an increased risk for intracranial aneurysm and aneurysmal subarachnoid hemorrhage.

    View full publication

    Read more
  • Heightened dream recall ability linked to increased creativity and functional brain connectivity www.psypost.org
    Brain Sleep

    People who frequently recall their dreams tend to be more creative.

    Dreams are a state of consciousness that occurs during sleep. Typically characterized by sensory, cognitive, and emotional experiences, dreams share many similarities with hallucinations. Scientists formerly believed that dreams only occurred during the rapid eye movement, or REM, stage of sleep, but recent research indicates that they can occur at any time during sleep. Findings from a recent study suggest that people who frequently recall their dreams tend to be more creative and exhibit increased functional connectivity in the brain’s default mode network.

    The default mode network is a collection of interconnected neural structures that demonstrate low activity when a person is engaged in a particular task but high activity when not. It also demonstrates activity when a person tries to remember past events or imagine future events. Although some evidence suggests that the default mode network is involved in self-focused, ruminative thought, other evidence suggests it is involved in creativity and spontaneous thought processes.

    The study involved 55 healthy adults (19 to 29 years old) who had normal sleep patterns. Roughly half of the participants reported that they frequently recalled their dreams, recalling about six dreams per week, and the other half reported that they rarely recalled their dreams, recalling fewer than one dream per week. All participants underwent functional magnetic resonance imaging (fMRI) scans while sleeping. Before their scans, they answered questions about their personality, anxiety levels, cognitive ability, and sleep quality. They also completed a battery of tests to gauge memory and creativity.

    They found that both groups of participants had similar personalities, anxiety levels, sleep quality, and cognitive abilities. But participants who frequently recalled their dreams performed better on creativity tests than those who rarely recalled their dreams, suggesting they had greater creative skills. The fMRIs revealed that frequent recallers also exhibited enhanced functional connectivity within the default mode network of their brains than infrequent recallers.

    These findings suggest that high recall of dreams is associated with greater creativity and functional connectivity in the default mode network of the brain, and this connectivity promotes creative thinking during both wakefulness and sleep. Learn more about the roles of dreams in creativity in this clip featuring Dr. Matthew Walker.

    Read more
  • Inadequate sleep may preferentially act as a trigger for visceral fat accumulation (randomized controlled crossover study) www.sciencedaily.com
    Diet Obesity Sleep Metabolic Syndrome Visceral Fat

    Inadequate sleep drives abdominal fat gains.

    Visceral fat is body fat that is stored in the abdominal cavity near the liver, pancreas, and intestines. The accumulation of visceral fat is linked to type 2 diabetes, insulin resistance, inflammatory diseases, certain types of cancer, cardiovascular disease, and other obesity-related conditions. Findings from a recent study suggest that not getting enough sleep increases the risk of developing excess visceral fat.

    Sleep is essential for human health. Not getting enough sleep or having poor, fragmented sleep promotes the development of many chronic illnesses, including cardiovascular disease, hypertension, diabetes, stroke, obesity, and depression. Scientists don’t fully understand the mechanisms that drive these effects, but some evidence suggests that disturbances in circadian rhythms play vital roles.

    The trial involved 12 healthy young adults (aged 19 to 39 years) who engaged in an in-patient sleep study. Participants were allowed to have either a full night of sleep (nine hours of sleep opportunity) or restricted sleep (four hours of sleep opportunity) for two weeks. After a three-month washout period, participants repeated the study with the opposite sleep experience. The investigators measured the participants’ caloric intake, energy expenditure, body weight, body composition, and fat distribution throughout the study period.

    They found that when participants were sleep-restricted, they consumed approximately 13 percent more protein and 17 percent more fat (translating to about 300 calories) daily, but their overall energy expenditure did not change. Sleep-restricted participants also gained weight. Much of this weight was in the abdominal area, with a 9 percent increase in total abdominal fat area and an 11 percent increase in visceral fat, compared to when they got a full night’s sleep.

    These findings suggest that insufficient sleep increases caloric intake and promotes weight gain and visceral fat increases. Learn more about the harmful health effects of insufficient sleep in this episode featuring sleep expert Dr. Matt Walker.

    Read more
  • Menopause disrupts sleep, accelerating biological aging www.sciencedaily.com
    Aging Sleep Genetics

    Menopause accelerates epigenetic aging.

    Menopause, which typically occurs around the age of 52 years, is the cessation of a female’s menstrual cycle and signifies the loss of reproductive capacity. Evidence suggests that early menopause increases the risk for age-related disease and premature death. Findings from a 2016 study suggest that menopause accelerates epigenetic aging.

    Epigenetics is a biological mechanism that regulates gene expression (how and when certain genes are turned on or off). Diet, lifestyle, and environmental exposures can drive epigenetic changes throughout a person’s lifespan to influence health and disease. Epigenetic age is based on a person’s DNA methylation profile and strongly correlates with their chronological age. However, some exceptions exist. For example, the epigenetic ages of semi-supercentenarians (people who live to be 105 to 109 years old) are markedly younger than their chronological ages.

    The investigators analyzed the DNA methylation profiles of more than 3,100 women enrolled in four large observational studies (Women’s Health Initiative; InCHIANTI; Parkinson’s Disease, Environment, and Genes; and the National Survey of Health and Development) to identify links between epigenetic age and menopause. Their analysis was based on assessment of the biological age of cells taken from the women’s blood, saliva, and inner cheek. Because the age at which a female experiences menopause is heritable, they conducted a Mendelian randomization analysis to identify genetic links between age at menopause and epigenetic aging.

    They found that menopause markedly accelerated epigenetic aging. Females who experienced earlier natural menopause were more likely to have “older” blood than those who experienced later menopause, but females who had surgical menopause (a surgical procedure in which the ovaries are removed) had older blood and saliva than those who experienced natural menopause. Cells taken from the inner cheek of females who took menopausal hormone therapies were younger than those who did not take hormones. They also found that a particular gene variant that influences the age at which a female experiences menopause also influences age acceleration.

    These findings suggest that menopause accelerates epigenetic aging in females. The investigators conceded that their findings do not establish a cause-and-effect relationship, however. In a related study, researchers found that menopause-related sleep disorders, such as insomnia or poor sleep quality, contribute to the accelerated aging associated with menopause. Learn more about accelerated epigenetic aging in this episode featuring Dr. Steve Horvath.

    Read more
  • Excess artificial light exposure increases risk of obesity in preschool aged children www.sciencedaily.com
    Obesity Sleep Circadian Rhythm Development Blue Light

    Artificial light exposure increases the risk for obesity among children. Light is the primary signal that entrains the body’s master clock to set its 24-hour circadian cycle. Consequently, the body is synchronized to external light-dark cycles. In recent decades, exposure to light from artificial sources (rather than natural ones) has increased, paralleling the global increases in obesity among adults. Findings from a 2016 study suggest that exposure to artificial light increases the risk for obesity among children.

    Global health experts estimate that more than 42 million children under the age of five years have obesity, roughly one-fourth of whom live in developing nations. Obesity increases a person’s risk for developing chronic diseases such as type 2 diabetes, heart disease, and some cancers. It also imposes considerable financial costs at the individual, healthcare system, and national level.

    The study involved 48 preschool-aged children receiving daycare services in Australia. The investigators measured the children’s baseline body mass index (BMI), sleep duration and timing, light exposure, and physical activity levels via clinical assessment, parent questionnaires, and light and activity trackers. They repeated these measures 12 months later.

    They found that at baseline, children who had longer early exposure to moderate intensity light (such as that from artificial sources) were more likely to have higher BMI, while children who had longer afternoon exposure to bright light (such as that from natural sources) tended to have lower BMI. At the second assessment, the investigators found that even after taking into account sleep duration and timing, BMI, and activity levels, children who had more total light exposure at baseline (due to having earlier exposure) gained more weight than their peers. Specifically, for every hour earlier that the children were exposed to light, they experienced a 0.6 unit increase in BMI. The investigators posited that although this was a small increase, it could be an indicator of a life-long trajectory toward weight gain.

    These findings suggest that greater light exposure, especially when it occurs early in the day from artificial light sources, contributes to weight gain in children. Interestingly, adults that receive early exposure to bright light typically sleep better – a key to maintaining a healthy weight. Learn more in this clip featuring Dr. Matthew Walker.

    Read more
  • Animal research suggests fragmented sleep promotes cancer through increases in TLR4 which polarize macrophages towards immune suppressive M2 type www.sciencedaily.com
    Cancer Sleep Immune System Toll-Like Receptors

    Poor sleep drives cancer growth by decreasing a type of immune cell that eliminates tumors.

    Scientists have long known that people who don’t get enough sleep are at greater risk of developing cancer. Once a person develops cancer, how long and how well they sleep can influence their disease outcome. A 2014 study implicated tumor-associated macrophages and toll-like receptor (TLR)- 4 as the primary drivers of unfavorable cancer outcomes in the setting of poor sleep.

    Tumor-associated macrophages are white blood cells that play important roles in cancer progression. M1 macrophages, which have a proinflammatory phenotype, can eliminate cancer cells. M2 macrophages, which have an anti-inflammatory phenotype, suppress immune activity and promote blood vessel growth – a critical aspect of tumor survival.

    TLR-4 is a receptor protein found on the surface of immune and other cells. TLR-4 activates transcription factors that promote the expression of pro-inflammatory cytokines. While this inflammatory response is necessary for immunity against bacterial infection, chronic activation of the TLR-4 pathway can accelerate aging and increase the risk for many diseases, including cancer.

    The investigators interrupted the sleep of normal mice and mice that lacked TLR-4, mimicking the effects of several sleep disorders. After the mice developed cancer, the investigators noted characteristics of the animals' tumors, including size, invasiveness, and the type and number of tumor-associated macrophages.

    They found that the mice that experience interrupted sleep had larger, more invasive tumors and larger numbers of tumor-associated macrophages than the mice that had uninterrupted sleep. However, these effects were not observed in the mice that lacked TLR4.

    These findings suggest that poor, fragmented sleep promotes tumor growth and invasiveness via activation of TLR4 pathways and subsequent recruitment of tumor-associated macrophages. Learn more about the varied roles TLR4 plays in human health in our overview article.

    Read more
  • Brain cells that regulate wakefulness may become overactive with age. www.newscientist.com
    Sleep

    Overactive neurons in the brain contribute to the poor sleep quality that often accompanies aging.

    Sleep is crucial for maintaining cognitive health throughout the lifespan. However, sleep quality often declines with age. Findings from a new study in mice suggest that overactive hypocretin neurons contribute to the poor sleep quality that often accompanies aging.

    Hypocretin, also known as orexin, is a type of neuropeptide – a signaling molecule composed of short amino acids and produced by neurons. Hypocretin is produced primarily in the hypothalamus, where it is involved in aspects of wakefulness and appetite.

    The investigators used optogenetics to study and record the activity of hypocretin-producing neurons in the brains of young and old mice. Optogenetics is a research technique that allows scientists to switch a neuron’s activity on or off using light and genetic engineering.

    They found that older mice had nearly 40 percent fewer hypocretin-producing neurons than younger mice. The remaining neurons, which were more excitable than those present in younger mice, triggered wakefulness and poor sleep. The investigators attributed these changes in the neurons to age-related loss of potassium channels (which regulate neuronal excitability) in the older animals' brains.

    These findings suggest that poor sleep that accompanies aging may be due to intrinsic changes in the number and activity of hypocretin-producing neurons, providing potential targets for sleep therapies in the future. Learn about some of the effects of age-related sleep loss in this episode featuring Dr. Matthew Walker.

    Read more
  • Not getting enough sleep increases common cold risk. jamanetwork.com
    Sleep Virus

    Sleep plays roles in many aspects of human health, including immune function. Not getting enough sleep can drive a chronic inflammatory state, increasing a person’s risk for both acute and chronic diseases. Findings from a 2009 study demonstrate that not getting enough sleep increases a person’s risk for developing a common cold.

    The average person experiences two to three colds every year, most of which are caused by rhinoviruses. Working adults in the United States tend to lose nearly nine work hours per cold due to absenteeism and on-the-job productivity losses. Adults caring for a child under the age of 13 years tend to lose at least one hour of work per cold. Together, these productivity losses equate to nearly $25 billion per year.

    The study involved 153 healthy men and women between the ages of 21 and 55 years. Over a period of two weeks, participants kept sleep diaries in which they reported how long they slept each night and how rested they felt upon waking. They also reported their “sleep efficiency,” the ratio of the total time spent asleep versus the total amount of time spent in bed. The study investigators then quarantined the participants and exposed them to RV-39, a type of rhinovirus that causes colds. They monitored the participants for five days to see if they developed cold symptoms.

    The investigators found that participants that had less than seven hours of sleep (on average) were three times more likely to develop a cold than those that had eight or more hours of sleep. Participants with less than 92 percent sleep efficiency were nearly six times more likely to develop a cold than those with 98 percent or higher sleep efficiency.

    These findings suggest that not getting enough sleep or having poor sleep efficiency increases a person’s risk for developing illnesses the common cold. Many people experience difficult falling or staying asleep, increasing their risk for colds and other diseases. Learn how cognitive behavioral therapy benefits people with sleeping problems.

    Read more
  • Memory reactivation during sleep enhances ability to recall faces and names. www.sciencedaily.com
    Sleep Memory

    Remembering a person’s face – and the name that goes with it – are fundamental aspects of social and professional relationships. Scientists think that, like many other aspects of memory, sleep plays an important role in the ability to recall faces and names. Findings from a new study suggest that targeted memory reactivation helps people recall faces and names.

    Targeted memory reactivation is an experimental tool that relies on context-dependent memory, a type of memory that occurs when contextual cues facilitate memory recall. It is based on the premise that during memory storage, contextual information, such as sounds, smells, or tastes, are also stored. Retrieval of the memories is enhanced when exposed to the context. Although smells are among the strongest cues for inducing and retrieving memories, sounds can also provide strong stimuli for learning.

    In the present study, 80 college-age students taking either a Latin-American history class or a Japanese history class heard their classmates' names while viewing pictures of the classmates' faces and listening to either Latin-American or Japanese music, respectively. Later, during a period of sleep, the students listened to softly played recordings of some of the names and the associated music. The investigators measured the participant’s sleep quality using electroencephalography and assessed the students' recall of their classmates' names while viewing their pictures.

    They found that the students' ability to place a name with a face was enhanced if they heard the name and the associated music during a period of sleep. However, students who experienced poor quality sleep performed worse on recall tests than those with good quality sleep.

    These findings suggest that targeted memory reactivation enhances memory consolidation, especially in the setting of deep, good quality sleep. Learn more about targeted memory reactivation in this clip featuring sleep expert Dr. Matthew Walker.

    Read more
  • Bedtime light exposure suppresses melatonin levels in children by 70 percent. onlinelibrary.wiley.com
    Sleep Melatonin

    Light is a major regulator of circadian rhythm, especially in children, whose eyes are more photosensitive. Previous research demonstrates that exposure to bright light suppresses melatonin (the sleepiness hormone) production twice as strongly in children as in adults. Authors of a new report found that children exposed to a wide range of light intensities experienced melatonin suppression that may decrease sleep quality.

    Light activates photosensitive cells in the retina that contain a pigment called melanopsin, which is most sensitive to blue light around 480 nanometers in wavelength. Melanopsin signaling is transmitted to a brain region called the suprachiasmatic nucleus, the master regulator of the circadian clock and a modulator of melatonin production. Previous research has demonstrated greater melatonin suppression in children exposed to home light levels (about 140 lux) compared to dim light (about 30 lux); however, additional studies are needed to understand how a wider range of light intensities affect melatonin suppression in young children.

    The researchers recruited parents of 36 children with good sleeping habits and asked them to complete a sleep diary for their children for seven days to assess baseline sleep quality. On the eighth day, the investigators transformed the participants' home into a dim-light environment by covering windows and installing low wattage light bulbs. Children entered the dim environment 4.5 hours before bedtime and the investigators measured their salivary melatonin levels every 20 to 30 minutes until one hour past bedtime. Children woke up in the morning and spent the entirety of the ninth day in the dim-light environment. One hour prior to bedtime, the investigators exposed children to light from an LED panel while playing and sampled melatonin levels again. The investigators set the LED panel to a single light intensity between 5 and 5,000 lux for each child based on a randomized pattern.

    During the one hour of light exposure prior to bedtime, salivary melatonin levels were suppressed by 69 to 98 percent across all light intensities; however, there was no overall dose-response. The investigators found that instead of light intensity and melatonin suppression changing at the same rate (as they do in a dose-response relationship), all light intensities induced high levels of melatonin suppression. Light intensities below 40 lux (i.e., dim light) tended to produce less melatonin suppression compared to intensities above 40 lux, but no other statistical trends were observed.

    These findings show that young children are highly susceptible to light before bedtime, especially light brighter than 40 lux (roughly equivalent to the amount of light provided by a 30 watt incandescent light bulb in a typical child’s bedroom). Further research is needed to understand how melatonin suppression relates to sleep quality.

    Read more
  • Shorter sleep duration promotes the intake of added sugars and carbohydrates. www.sciencedaily.com
    Sleep Sugar

    Sleep is essential for maintaining optimal physical health. Evidence suggests that adults who don’t get enough sleep have a greater risk of developing many chronic diseases and tend to overeat. Findings from a recent study suggest that teens consume more sugar when they don’t get enough sleep.

    Sleep patterns change markedly during the adolescent years, driven by shifts in circadian rhythms and subsequent sleep latency – the tendency to fall asleep later in the evening than adults or young children. Social and behavioral factors play roles, as well, as teens often participate in evening social events and exert autonomy over their bedtimes. Consequently, most teens get fewer than the recommended eight hours of sleep per night.

    The study involved 93 healthy adolescents between the ages of 14 and 17 years. The participants experienced two sleep conditions, each lasting five nights. In the “healthy sleep” condition, they had 9.5 hours of sleep opportunity; during the “short sleep” condition, they had 6.5 hours of sleep opportunity. The participants wore sleep trackers and provided information about the types, quantities, and timing of foods they ate while experiencing each sleep condition.

    The trackers revealed that, on average, the participants slept more than two hours longer when they experienced the healthy sleep condition. When participants experienced the short sleep condition, they tended to consume more carbohydrates, added sugars, and sweet drinks, and fewer fruits and vegetables than when they experienced the healthy sleep condition. The increase in added sugars was particularly concerning, because added sugars are associated with weight gain. Interestingly, the patterns of higher consumption emerged late at night – after 9 p.m.

    These findings suggest that teens who don’t get enough sleep consume more sugars late at night, potentially promoting weight gain and driving other health problems, such as obesity or diabetes. Learn more about the harmful effects of eating sugars in this podcast featuring Dr. Rhonda Patrick.

    Read more
  • Compounds in herbs and tea improve sleep and daytime functioning. pubmed.ncbi.nlm.nih.gov
    Sleep

    Plant-based dietary compounds exert a wide range of beneficial health effects on humans, likely due to their antioxidant, anti-cancer, and anti-inflammatory properties, among others. Evidence from a recent study suggests that plant-based compounds rosmarinic acid and epigallocatechin gallate (EGCG) improve sleep and daytime function in people with poor sleep.

    Rosmarinic acid is found in many culinary herbs, including rosemary, oregano, sage, thyme, and peppermint. Evidence suggests it influences sleep by regulating neurotransmitters in the brain such as GABA and acetylcholine. EGCG is found in tea. It exerts potent antioxidant, anti-cancer, and anti-proliferative properties. EGCG suppresses neuroendocrine pathways involved in alertness, thus providing anti-anxiety and hypnotic effects.

    Roughly one-third of adults in the United States report having poor or insufficient sleep. Not getting good quality or sufficient sleep increases a person’s risk of developing many chronic illnesses and is associated with mood disturbances, memory impairments, and cognitive dysfunction. Many people who have sleep problems take sleeping pills, which can cause cognitive impairments and daytime sleepiness.

    The intervention study involved 89 healthy adults (average age, 31 years) who reported having poor sleep. Half of the participants took a blend of rosmarinic acid and EGCG (providing at least 65 milligrams of the two combined) in capsule form every night before bed for 30 days, while the other half took a placebo. Participants' caffeine intake and physical activity were not prohibited, but the amount and timing were restricted. The study investigators monitored the participants for changes in sleep (via sleep diary and activity tracker), mood, and neurocognitive functioning.

    The investigators found that participants who took the rosmarinic and EGCG blend experienced better sleep quality and less severe insomnia than those who took the placebo. In addition, those who took the blend did not exhibit any cognitive impairments, but they did demonstrate improvements in daytime attention, working memory, and risk assessment.

    These findings suggest that a blend of rosmarinic acid and EGCG enhances sleep and improves daytime cognitive performance in people with poor sleep. Learn how getting a good night’s sleep reduces your risk of dementia in this video featuring Dr. Rhonda Patrick.

    Read more
  • Perceptions of sleep depth don't correlate with sleep phase. medicalxpress.com
    Sleep

    Sleep scientists generally categorize the various phases of human sleep as REM (rapid-eye movement – the period when dreams occur) and NREM (non-rapid-eye movement – the period typically described as “deep sleep”). Subjective perceptions of sleep and sleep quality or “depth” vary, however. Findings from a recent study suggest that some people’s perceptions of how deeply they sleep don’t align with objective measures of their sleep.

    Objective measures of sleep quality are based on multiple physiological and neurological parameters that gauge the depth, quality, and duration of a person’s sleep. Typical measures include assessments of brain waves (via electroencephalogram, or EEG), heart rate, and respiration rate, among others.

    The authors of the study recruited 20 healthy adults (average age, 38 years) who considered themselves good sleepers and 10 healthy adults of similar ages who had insomnia. While the participants slept, the authors measured the participants' brain waves via EEG, periodically waking them to obtain subjective assessments of their sleep depth and quality.

    The good sleepers reported that their sleep was lightest in the first two hours of NREM sleep (generally considered “deep sleep”) and deepest during REM sleep. Conversely, participants with insomnia reported feeling awake more often during the first two hours of NREM sleep and often reported having lighter REM sleep. Interestingly, the EEGs revealed that the participants with insomnia were asleep during periods when they reported being awake. During periods of subjective deep sleep, participants reported having dream-like mental activity.

    These findings suggest that subjective perceptions about how deeply a person is sleeping don’t necessarily align with the phase of sleep they are in. Such findings could have relevance for future sleep studies, especially those aimed at improving sleep quality for people with insomnia.

    Read more
  • Intense exercise before bedtime does not impair sleep quality. www.sciencedaily.com
    Exercise Sleep

    Sleep is essential for both mental and physical health. Not getting enough sleep increases a person’s risk of developing many chronic illnesses, including cardiovascular disease, kidney dysfunction, hypertension, diabetes, stroke, obesity, and depression. More than a third of all adults living in the United States don’t get enough sleep. Findings of a recent analysis suggest that high intensity exercise does not impair sleep.

    Exercise and sleep are intrinsically linked. Evidence suggests that people who exercise tend to fall asleep more quickly and have better quality sleep than non-exercisers. However, sleep experts often caution against engaging in high intensity exercise less than three hours before bedtime to prevent sleep impairment due to exercise’s effects on circadian rhythmicity as well as other effects.

    The authors of the analysis reviewed data from 15 studies involving 194 healthy adult participants who engaged in high-intensity exercise before bedtime versus non-exercisers. The participants, who were between the ages of 18 and 50 years, reported regular, good sleep quality.

    When exercisers completed an acute bout of high-intensity exercise one-half hour to four hours before bedtime, their rapid eye movement sleep decreased, compared with non-exercisers, but no other significant sleep changes occurred. Similarly, engaging in regular high-intensity exercise in the evening two to four hours before bedtime did not disrupt sleep.

    These findings suggest that high-intensity exercise before bedtime does not impair sleep onset or quality. Many factors influence sleep onset and quality, however, including room temperature and light exposure. Learn more about these factors in this episode featuring sleep expert Dr. Matt Walker.

    Read more
  • Exercise restores cognitive losses caused by sleep deprivation. www.sciencedirect.com
    Exercise Brain Sleep

    Chronic sleep deprivation, a risk factor for cardiovascular and Alzheimer’s diseases, is common among adults in industrialized nations, with many reporting less than seven hours of sleep each night during the workweek. Acute sleep deprivation impairs cognitive function, working memory, attention, and executive function, increasing the rate of mistakes made while driving, at work, and at home. A recent report details the effects of aerobic exercise on cognitive function following a night of sleep deprivation.

    Sleep deprivation has been shown to decrease brain oxygen saturation, contributing to cognitive impairment. However, previous research has demonstrated that aerobic exercise increases blood flow to the prefrontal cortex, activating key brain regions that improve cognitive function. Enhanced blood flow to the brain during exercise increases oxygen saturation in brain tissue and improves energy metabolism.

    In this study, the researchers recruited 12 participants (average age, 21 years) and measured their baseline maximum aerobic capacity while riding a stationary bicycle. On a separate study visit, participants completed cognitive testing and answered questionnaires before and after cycling for 20 minutes at 60 percent of their maximum aerobic capacity. Participants wore an electrode cap on their heads during exercise to measure electrical activity in the brain. They completed this study visit twice in random order, once after a full night of rest and once following a night of total sleep deprivation.

    Sleep-deprived participants reported feeling sleepier and performed significantly worse on cognitive tests prior to exercise. Following exercise, both sleepiness and cognitive function were improved in both groups, although cognitive scores were still comparatively worse in the sleep-deprived group. Under both rested and sleep-deprived conditions, blood flow to the prefrontal cortex increased within 12 minutes of initiating exercise and was maintained until the end of exercise. However, the researchers did not find a relationship between oxygenation levels and cognitive function, so whether exercise-induced brain oxygenation had a beneficial effect on cognitive function is unclear.

    The authors concluded that exercise corrects the cognitive impairment induced by sleep deprivation, although future research is needed to identify the best exercise protocol to maximize the benefits on brain oxygenation following sleep deprivation.

    Read more
  • The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment www.ncbi.nlm.nih.gov
    Sleep

    Poor sleeping habits impair normal cognitive and metabolic function and are associated with worse mental and physical health outcomes in the short- and long-term. Sleep loss may also interfere with protein synthesis, driving skeletal muscle losses, a risk factor for obesity, type 2 diabetes, and frailty. Authors of a recent report measured the effects of sleep deprivation on muscle protein synthesis.

    Skeletal muscle is metabolically active. Having more muscle mass promotes insulin sensitivity and reduces the risk of developing type 2 diabetes. Previous research in rats has shown that sleep deprivation reduces the activity of enzymes that build muscle, such as testosterone and insulin-like growth factor (IGF)-1, and increases the activity of enzymes that break down muscle, such as cortisol. The same shift in hormones may occur in humans deprived of sleep.

    Thirteen young adults (average age, 21 years) completed two testing days in random order in which they experienced one night of sleep deprivation and one night of normal sleep. On one day, participants consumed a standardized meal at home at 7 p.m., reported to the laboratory at 9 p.m., and were not permitted to sleep until 7 a.m. During the night, participants were allowed to engage in quiet activities and eat low-protein fruits and vegetables as snacks. On the other day, participants consumed a standardized meal at home at 7 p.m., then slept at home between 10 p.m. and 7 a.m.. On both days, researchers collected blood samples and muscle tissue samples, following a standardized breakfast meal.

    One night of sleep deprivation reduced muscle protein synthesis by 18 percent. This was accompanied by a significant 24 percent reduction in serum testosterone levels in male participants and a significant 21 percent increase in cortisol levels in all participants. There was no difference in plasma insulin or IGF-1 levels and no difference in markers of muscle protein degradation.

    The authors concluded that just one night of sleep deprivation interferes with muscle protein synthesis. Chronic sleep deprivation may cause loss of muscle mass due to long-term suppression of muscle-building enzymes.

    The good news is exercise is known to counter at least some of the negative effects that sleep loss has on metabolism. For example, high-intensity interval training before a night of sleep deprivation attenuated the increase of glucose, insulin, and free fatty acids caused by lost sleep in healthy males.

    Read more
  • Waking just one hour earlier decreases depression risk. www.sciencedaily.com
    Sleep Depression

    Good sleep habits are important for maintaining good physical and mental health. Epidemiological studies have revealed a decreased risk of major depressive disorder in those who prefer to wake up early and go to sleep early. Authors of a report recently released studied the genetic associations between early sleep/wake preference and depression.

    Depression is a disease with multiple contributing factors that include environmental, lifestyle, and genetic influences. Untangling the web of factors contributing to late sleep preference and depression risk may help identify interventions to treat depression.

    Earlier sleep and wake times align better with typical work and social schedules, increase daily light exposure, and enhance sensitivity to rhythmic changes in brain activity, contributing to a lower risk of depression. While environmental and social factors may dictate a person’s wake and sleep schedule, genetic factors may also play a role in sleep timing preferences.

    The authors performed a genome-wide association study, which is an observational study where researchers look for associations between gene variations called single-nucleotide polymorphisms and disease prevalence. The authors collected genetic data and depression status from over 500,000 participants in the Psychiatric Genomics Consortium and United Kingdom Biobank studies to determine genetic proxies for depression. They also collected genetic and sleep data from over 700,000 participants in the United Kingdom Biobank and 23andMe research studies to determine genetic proxies for sleep time preference. Some participants wore an activity monitor to measure their sleep precisely. The researchers calculated the sleep midpoint (halfway between falling asleep and waking) and used this in their model of genetic data as well.

    Participants with an earlier sleep preference were 23 percent less likely to have depression. This decreased risk was additive for every hour that the midpoint of sleep occurred earlier in the night. That means shifting sleep one hour earlier at night and waking one hour earlier in the morning may decrease depression risk, but shifting the sleep window even earlier may decrease risk even more. The relationship between early or late waking preference and depression was significant for both physician-diagnosed and self-reported depression.

    The authors concluded that the association between genetics, sleep, and depression revealed by their study provides support for sleep interventions in patients with depression.

    Read more
  • Inadequate sleep increases a person's risk of developing Alzheimer's disease and dementia. neurosciencenews.com
    Alzheimer's Sleep Dementia

    Sleep is essential for human health. Not getting enough sleep or having poor, fragmented sleep increases a person’s risk of developing many chronic illnesses, including cardiovascular disease, hypertension, diabetes, stroke, obesity, and depression. Findings from a new study suggest that inadequate sleep increases a person’s risk of developing Alzheimer’s disease and dementia.

    Alzheimer’s disease and dementia are age-related disorders characterized by memory loss, cognitive decline, and behavioral changes. Nearly 50 million people are living with Alzheimer’s disease or a related dementia worldwide, a number expected to triple by the year 2050.

    The authors of the study drew on data from the National Health and Aging Trends Study, an on-going longitudinal study of adults living in the United States who are over the age of 65 years. More than 2,800 participants (average age, 76 years) completed questionnaires about their sleep quality, including time to sleep onset, sleep duration, and snoring. The authors collected information about the participants' cognitive health or death from any cause for up to five years after completion of the questionnaires.

    They found that participants who reported getting fewer than five hours of sleep per night were twice as likely to develop dementia compared to those who had seven to eight hours of sleep per night. Taking a long time to fall asleep (more than 30 minutes) increased the risk of dementia 45 percent. The authors also found that getting fewer than five hours of sleep per night, daytime sleepiness, and regular napping increased the risk of all causes of premature death.

    These findings indicate that short sleep duration and sleep-associated problems among older adults increase the risk of developing dementia and dying prematurely. The research of sleep expert Dr. Matthew Walker focuses on identifying certain windows of vulnerability during a person’s life when interventions might improve sleep quality to prevent or delay age-related cognitive decline. Learn more in this clip.

    Read more
  • Sleep deprivation mimics symptoms of post-concussion syndrome. news.osu.edu
    Sleep

    A concussion is a type of brain injury that causes temporary loss of brain function. Concussions are common among student athletes and can affect memory, judgment, reflexes, speech, balance, and coordination. Findings from a recent study suggest that sleep deprivation mimics many of the symptoms of post-concussion syndrome.

    Post-concussion syndrome is a condition in which the symptoms of concussion linger far beyond the expected recovery period, lasting months or even years after the original injury. Between 10 and 20 percent of people who experience concussion will have post-concussion syndrome.

    The study was part of the NCAA-U.S. Department of Defense Concussion Assessment, Research, and Education Consortium, an ongoing project investigating the effects of concussion and repetitive head impact. More than 30,000 military cadets and university student athletes provided demographic data as well as information on current and previous sport participation, concussion history, and preexisting personal and medical history.

    They also completed the Sport Concussion Assessment Tool–3rd Edition (SCAT3) symptom evaluation as part of baseline preseason testing. The SCAT3 is a self-reported inventory of 22 symptoms and includes questions about the number of hours of sleep obtained the night before testing.

    The majority of the participants (63 percent of the men and 74 percent of the women) reported having at least one symptom, the most common of which was fatigue or low energy. A subset of the cadets (18 percent of the men and 28 percent of the women) and the university students (11 percent of the men and 20 percent of the women) reported having enough symptoms to meet the diagnostic criteria for post-concussion syndrome. A common denominator among this subset was sleep deprivation (fewer than five hours) the night before the assessment.

    These findings suggest that many of the symptoms people report after a concussion are fairly common among cadets and university athletes who have not sustained a recent injury. They also highlight the need to take sleep and other environmental factors into consideration when determining whether athletes are ready to return to activity.

    Read more
  • Exercise counteracts the harmful effects of sleep deprivation. www.sciencedirect.com
    Exercise Sleep

    Exercise and other forms of physical activity elicit a wide range of beneficial health effects, including improvements in glucose tolerance and mitochondrial function. Findings from a new study suggest that high-intensity exercise compensates for the harmful effects of sleep deprivation.

    Sleep is critical for our mental and physical well-being. Sleep deprivation increases our risk of developing many chronic illnesses, including cardiovascular disease, kidney dysfunction, hypertension, diabetes, stroke, obesity, and depression. More than a third of all adults living in the United States report regular short sleep duration.

    The intervention study involved 24 healthy young men between the ages of 18 and 40 years. The study’s investigators placed the men into one of three groups: normal sleep (eight hours per night, for five nights); sleep restriction (four hours per night, for five nights); and sleep restriction/exercise (four hours per night, for five nights plus three high-intensity interval exercise sessions on a cycle ergometer). They assessed the participants' glucose tolerance, mitochondrial function, sarcoplasmic protein synthesis (a proxy for mitochondrial protein synthesis), and skin temperature before and after the intervention. Sarcoplasmic protein synthesis and skin temperature fluctuate in a diurnal manner due to circadian rhythms, which are altered with poor sleep.

    The men who experienced sleep restriction had reduced glucose tolerance and mitochondrial function. They also exhibited reduced amplitude of diurnal rhythms. However, the men who experienced sleep restriction but engaged in high-intensity exercise did not exhibit any of these effects.

    These findings demonstrate that high-intensity exercise may counteract the harmful effects of sleep deprivation and suggest that clinicians should recommend exercise to patients who experience poor sleep as a means to improve metabolic health.

    Read more
  • Antibiotic use disrupts sleep/wake cycles in mice www.sciencedaily.com
    Microbiome Sleep

    Many adults struggle with daytime sleepiness and nighttime insomnia, impairing memory, mood, and focus. Several factors regulate sleep and wake activities, including central and peripheral circadian rhythms and timing of meals. These rhythms also regulate the diurnal activities of the gut microbiota. New research reports that antibiotics, which can alter the gut microbial population, may disrupt normal sleep cycles in mice due to changes in neurotransmitters.

    The human gut is an important site for the production and metabolism of neurotransmitters like serotonin. Neurotransmitters in the gut regulate digestive processes, communicate with the brain directly through the enteric nervous system, and interact with the microbiome. Serotonin is important for regulating sleep/wake cycles, and too little serotonin may decrease sleep quality.

    The scientists gave mice water containing broad spectrum antibiotics for four weeks to deplete their gut microbiota or normal drinking water. They used implantable electrodes to collect detailed sleep pattern data in the mice and measured concentrations of metabolites in the animals' guts and feces.

    The authors reported significant alterations in metabolites related to vitamin, amino acid, and neurotransmitter metabolism in mice whose microbiota had been depleted with antibiotics. These mice exhibited less time in deep sleep during the day (when these nocturnal animals should be sleeping) and more time in deep sleep during the night. They also experienced frequent transitions between rapid eye movement (REM) sleep and non-REM deep sleep, an indicator of decreased sleep quality. The authors suggested this may have been caused by lower levels of serotonin in the gut due to depletion of vitamin B6, a necessary cofactor for producing serotonin.

    This research could have important implications for human health. The authors noted that other research has demonstrated the ability of some prebiotics (fiber and nutrients that are beneficial for the gut microbiota) to improve sleep in humans.

    Read more
  • Lack of sleep causes poor emotional control journals.sagepub.com
    Sleep

    Currently selected for this coming member’s digest by team member Melisa B.

    Getting an adequate amount of quality sleep is increasingly recognized as vital for mental and physical health. Sleep deprivation can increase stress hormones associated with anxiety and depression and greater risk of chronic diseases like cardiovascular disease. A recent randomized trial found that a night of sleep deprivation can impair a person’s ability to ignore intrusive thoughts.

    Intrusive thoughts include unpleasant memories, images, or worries that are difficult to ignore or suppress. These types of thoughts can cause low mood and difficulty focusing on important tasks. They are common features of mental illnesses such as major depressive order and post-traumatic stress disorder.

    Poor sleep impairs brain function through a number of mechanisms such as influencing heart rate variability, the variation in time between heart beats. Low heart rate variability indicates greater fight-or-flight response by the autonomic nervous system and is associated with an increased cardiovascular disease risk. Poor sleep is known to decrease heart rate variability.

    The investigators trained a group of 60 participants to associate a set of emotionally negative and neutral scenes with human faces. Then they assigned participants to a night of normal sleep or total sleep deprivation. The next morning participants completed a task called “Think/No Think,” where they were shown a face from the previous day and asked to recall or suppress the scene associated with that face. Their ability to control memory retrieval and suppression was self-reported. The investigators also measured heart rate variability before the task using electrocardiography.

    Participants in the sleep deprivation group reported that they were unable to suppress intrusive thoughts about 50 percent more often than the control group. The authors define intrusive thoughts as memories of scenes from the previous day that the researchers asked participants to suppress during the task. For participants in the well-rested group, higher heart rate variability was predictive of better intrusive thought suppression.

    Normally, the prefrontal cortex controls areas of the brain important emotional regulation, the amygdala, and memory, the hippocampus. The authors suggested the intrusive thoughts experienced by sleep-deprived participants are caused by an increase in fight-or-flight response and subsequent loss of control by the prefrontal cortex, a hypothesis supported by existing literature. They advised that future research should include brain imaging to confirm these results.

    Read more
  • Long-term poor sleep predicts amyloid-beta deposition in the brain. www.the-scientist.com
    Alzheimer's Sleep

    Sleep disruption is linked with the pathophysiology of Alzheimer’s disease, with characteristic changes in sleep emerging early in life, well before the clinical onset of the disease. A key player in the development of Alzheimer’s disease is amyloid-beta. Insufficient sleep increases the production of amyloid-beta, and amyloid-beta deposition, in turn, impairs sleep in a vicious, self-perpetuating loop. Findings from a new study demonstrate that chronic poor sleep predicts the degree of amyloid-beta deposition in the brain.

    The study involved 32 older adults (average age, 73 years) who were cognitively intact. The authors of the study analyzed the participants' sleep patterns at the beginning of the four-year study. At periodic intervals throughout the study, the authors measured the participants' cognitive function and performed positron emission tomography (PET) scans to check for the presence of amyloid-beta in the participants' brains.

    They found that most of the participants already had some amyloid-beta accumulation in their brains, but this was not surprising, considering the participants' ages. They also found that participants who had less slow wave sleep and poor sleep efficiency were more likely to have faster accumulation of amyloid-beta.

    These findings demonstrate that objective markers of sleep could forecast the rate of amyloid-beta deposition in the human brain.

    Read more
  • Lithium blocks some of the sleep disturbances, memory loss, and learning problems tied to fetal alcohol syndrome in mouse study www.sciencedaily.com
    Sleep Alcohol Memory Pregnancy Development Lithium BDNF

    From the article:

    The new study found that giving the drug to newborn mice 15 minutes after “binge” alcohol consumption eliminated the hyperactivity and sleep deficits seen when rodents exposed to alcohol became adults. Moreover, the researchers report, lithium chloride-treated mice were much less likely to show the 25 percent drop in memory and cognitive test scores seen in untreated mice given the same amount of alcohol.

    “Our study showed that lithium chloride prevented many of the damaging neurological effects of alcohol abuse on the still-developing brain, especially the impact on the parts of the brain controlling sleep,” says co-senior study investigator Donald Wilson, PhD.

    Promoting BDNF as one pathway to brain cell survival:

    “Lithium chloride is known to block many pathways that lead to brain cell death, while promoting others that lead to survival, like brain-derived neurotrophic factor, or BDNF,” says Saito, a research assistant professor at NYU Langone. Further experiments are needed, she says, to determine if chemicals that stimulate BDNF production also blunt the effects of alcohol abuse in newborn mammals.

    Note: increased BDNF seems to actually be a natural mechanism by which the brain responds to reduce damage of BDNF

    Read more
  • A disrupted sleep-wake cycle may be an early warning sign of Parkinson's disease. www.sciencedaily.com
    Parkinson's Sleep Circadian Rhythm

    Parkinson’s disease, or PD, is a neurodegenerative disorder identified by the death of dopamine-producing neurons in the part of the brain that controls movement. The disease typically manifests later in life and is characterized by tremors and a shuffling gait. However, other regions of the brain are also affected, and sleep disturbances are a common non-motor feature of PD. Findings from a new study suggest that a disrupted circadian rhythm is a risk factor for PD.

    The circadian rhythm is the body’s 24-hour clock that modulates a wide array of physiological processes, including the production of hormones that regulate sleep, hunger, metabolism, and others, ultimately influencing body weight, performance, and susceptibility to disease. As such, circadian rhythmicity may have profound implications for human healthspan. The circadian rhythm changes with age and older adults have less deep, more fragmented sleep. Alterations in the circadian rhythm are more profound in people with PD, even in the early stages of the disease before symptoms develop.

    Previous research in animals has demonstrated that damage to circadian-related neurons occurs during the presymptomatic stages of PD. The current study investigated whether a disordered circadian rhythm in later life is associated with an increased risk of developing PD in humans.

    In a longitudinal prospective study, the authors recruited 2,930 healthy, community-dwelling older men without PD. The authors measured the rest-activity rhythms of the participants by having them wear a device on their wrist that measured activity, known as an actigraph. The authors collected recordings of activity and sleep patterns over three continuous 24 hour periods and plotted them on a graph for each participant. During the following 11 years, the men were asked if they had received a PD diagnosis and whether they were taking medications for the disease. The actigraphs revealed that participants with a less robust circadian rhythm, as evidenced by features including reduced activity and drowsiness during the day and fragmented sleep, had an increased risk of developing PD over the subsequent 11-year period.

    These findings suggest that an altered circadian rhythm may occur years in advance of clinical signs of PD and might be a useful prognostic marker. Even for community-dwelling older adults, reduced daily activity, daytime drowsiness, and fragmented sleep may be signals that warrant attention. Further research is needed to determine if these findings also apply to women and younger individuals.

    Read more
  • Recovery sleep after a period of sleep deprivation restores hippocampal activity but not the ability to form memories. www.nature.com
    Brain Sleep

    Sleep facilitates the storage of new information in the hippocampus – the region of the brain responsible for the formation and consolidation of short-term memories. Poor sleep, however, inhibits the brain’s ability to form memories. Findings from a new study demonstrate that two nights of recovery sleep after a period of sleep deprivation restores hippocampal activity but not the ability to form memories.

    Sleep deprivation increases a person’s risk of developing many chronic illnesses, including cardiovascular disease, kidney dysfunction, hypertension, diabetes, stroke, obesity, and depression. More than a third of all adults living in the United States report having poor sleep habits.

    The study involved 39 healthy adults who participated in a controlled in-laboratory sleep protocol. Each of the participants experienced one night of sleep deprivation followed by two consecutive nights of recovery sleep. The authors of the study used standard recognition tests to assess the participants' ability to form memories at baseline and every day thereafter. They used functional magnetic resonance imaging (fMRI) to assess the participants' hippocampal functional connectivity at baseline, after sleep deprivation, and after recovery sleep.

    After a single night of sleep deprivation, the participants' memory performance was markedly worse. Similarly, the fMRIs revealed that the participants' hippocampal connectivity was impaired in several regions of the brain associated with memory formation.

    After two nights of recovery sleep, hippocampal connectivity was restored, but memory performance was still impaired. These findings suggest that a person needs more than two nights of recovery sleep to restore memory function after just one night of sleep loss.

    Other studies have demonstrated the effects of sleep deprivation on academic performance. Watch this clip in which sleep expert Dr. Matthew Walker describes the role that sleep plays in learning and new memory formation.

    Read more
  • Fragmented sleep contributes to increased risk of atherosclerosis. news.berkeley.edu
    Sleep Heart Disease

    Atherosclerosis is a disease of the arteries characterized by the deposition of fatty plaques on the arteries' inner walls. Roughly half of all deaths in developed countries are attributed to atherosclerosis. A new study suggests that a pro-inflammatory pathway triggered by poor sleep contributes to the risk of developing atherosclerosis.

    The study involved more than 1,600 ethnically and racially diverse adults (average age, 68 years) enrolled in the Multi-Ethnic Study of Atherosclerosis. The authors of the study measured the participants' home sleep and activity levels over a period of a week and assessed their brain activity during one night in a sleep laboratory. They also ran blood tests to identify biomarkers associated with disease processes and determined the participants' coronary artery calcification scores, which provide reliable measures of atherosclerosis.

    They found that poor, fragmented sleep led to increased levels of proinflammatory molecules and white blood cells (neutrophils and monocytes). Together, these factors promote inflammation, a key driver in the pathogenesis of not only atherosclerosis but many other diseases as well. Poor sleep also predicted the degree of coronary artery calcification. Their findings held true even after ruling out factors related to age, ethnicity, gender, body mass index, sleep disorders, blood pressure, and smoking.

    These findings underscore the fact that sleep has far-reaching effects on many aspects of health. Learn more in this clip featuring sleep expert Dr. Matthew Walker, in which he describes how the different stages of sleep influence both mental and cardiovascular health.

    Read more
  • Chronic sleep deprivation impairs immune function. www.sciencedaily.com
    Sleep

    Sleep deprivation is associated with many chronic health conditions, including Alzheimer’s disease, cardiovascular disease, and type 2 diabetes. Roughly one-third of all adults living in the Unites States are sleep-deprived. A recent study demonstrates that sleep deprivation impairs the body’s immune response, providing a link between inadequate sleep and chronic disease.

    How much sleep a person needs is largely dependent on their chronotype – an individual’s innate tendency to sleep at a particular time during a 24-hour period. Chronotypes are based on circadian rhythms and are genetically determined, making it difficult to identify proper controls for sleep studies.

    To address this problem, this study involved 11 pairs of monozygotic (identical) twins whose self-reported sleep patterns differed by at least 60 minutes per night. The authors of the study monitored the participants' sleep and analyzed their gene expression profiles.

    The average sleep duration for all the study participants was roughly seven hours and 20 minutes per night. The average sleep duration difference among the twin pairs was one hour and four minutes. Gene expression profiles differed between the twins, as well. In particular, poor sleep altered gene expression of factors involved in the immune response of white blood cells. These alterations could contribute to the dysregulated immunity often observed in sleep-deprived people.

    Read more
  • Japanese sake yeast supplementation improves sleep quality in a double-blind randomized controlled clinical trial. www.ncbi.nlm.nih.gov
    Sleep Blood Pressure

    An abundance of scientific evidence points to the many roles that sleep plays in maintaining our mental and physical health. Not getting enough sleep is associated with increased risk for many chronic diseases, including high blood pressure, stroke, and cancer. Although many pharmaceutical sleep aids are available, they carry risks and do not provide good quality sleep. A recent study suggests that supplementation with sake yeast, a natural food product that is used to make Japanese wine, improves non-rapid eye movement sleep in humans by activating adenosine receptors.

    Sleep occurs in distinct stages, the most prominent of which is non-rapid eye movement (NREM) sleep – typically referred to as “deep sleep” or “slow-wave sleep.” It comprises approximately 75 to 80 percent of a person’s total sleep time and is characterized by slowed brain waves, heart rate, and respiration. During NREM sleep, the body produces growth hormone, which plays roles in metabolism.

    Adenosine is a nucleoside compound present in every cell of the body. It plays important roles in energy metabolism and utilization. When adenosine binds to adenosine receptors in the brain, it promotes NREM sleep.

    After first determining that sake yeast activated adenosine receptors in a human cell line, the authors of the study conducted a double‐blind placebo‐controlled crossover trial involving 68 healthy men and women (average age 38 years old). Each participant took 500 milligrams of sake yeast or a placebo in tablet form for four days, one hour prior to their normal bedtime. After a 3-day washout period, the procedure was repeated with the participants who received the placebo taking the yeast and vice versa. Throughout the study, each participant completed a questionnaire to assess the subjective measures of their sleep quality. They also provided electroencephalography (EEG) data via portable EEG device and urine samples (to measure growth hormone excretion) to gauge objective measures of sleep quality.

    The participants who took the sake yeast supplements reported improvements in their subjective ratings of sleep and fatigue. The EEG data revealed that the sake yeast supplementation increased key aspects of slow‐wave sleep by 110 percent without altering other sleep parameters. In addition, their urinary excretion of growth hormone increased by 137 percent. These findings suggest that sake yeast supplementation is an effective and safe way to promote high‐quality, deep sleep.

    Read more
  • Sleep duration may influence children's mental health. warwick.ac.uk
    Sleep Depression Mental Health

    Sleep is critical for our mental and physical well-being. Sleep deprivation increases our risk of developing many chronic illnesses, including cardiovascular disease, kidney dysfunction, hypertension, diabetes, stroke, obesity, and depression. More than a third of all adults living in the United States report regular short sleep duration. Data from a recent study suggest that children are particularly vulnerable to sleep deprivation.

    The American Academy of Pediatrics recommends that children between the ages of six and 12 years should sleep nine to 12 hours every night for optimal health. Inadequate sleep in children is associated with poor mental and physical health.

    The authors of the study analyzed structural MRI data from more than 11,000 children between the ages of nine and 11 years who were enrolled in the Adolescent Brain Cognitive Development (ABCD) Study. They also assessed the children’s cognitive performance and mental health status. The parents of the children in the study provided information about their child’s sleep duration by answering the question, “How many hours of sleep does your child get on most nights?”

    The study revealed that children who had shorter sleep duration were more likely to experience depression and anxiety and were more likely to exhibit impulsive behavior and poor cognitive performance. The association between poor sleep and depression persisted and were observed at the one-year follow-up. In addition, the volume of the orbitofrontal cortex, prefrontal and temporal cortex, precuneus, and supramarginal gyrus regions of the sleep-deprived children’s brains were lower than children who received adequate sleep.

    These findings underscore the importance of adequate sleep for proper brain function, especially in the developing brain.

    Read more
  • One night of sleep deprivation in healthy young men caused increased blood levels of tau, a protein that forms tangles in the brain. www.eurekalert.org
    Alzheimer's Sleep Neurons Protein

    Sleep disruption is intrinsically linked with Alzheimer’s disease and its pathophysiology, with characteristic changes in sleep emerging early in life, well before the clinical onset of the disease. A key player in the development of Alzheimer’s disease is amyloid-beta. Insufficient sleep increases the production of amyloid-beta, and amyloid-beta deposition, in turn, impairs sleep in a vicious, self-perpetuating loop. Findings from a new study demonstrate that sleep deprivation also increases blood levels of tau, a protein found in the brain.

    Tau is a microtubule-bound protein that forms the neurofibrillary “tau tangles” associated with Alzheimer’s disease. Tau tangles disrupt the transport of metabolites, lipids, and mitochondria across a neuron to the synapse where neurotransmission occurs. Diminished slow-wave sleep is associated with higher levels of tau in the brain. Elevated tau is a sign of Alzheimer’s disease and has been linked to cognitive decline.

    The two-condition crossover study involved 15 healthy young men who were randomized to regimens of either two nights of consecutive sleep or one night of sleep followed by one night of sleep deprivation. Following the one night of sleep deprivation, participants' blood levels of tau increased approximately 17 percent, compared to an approximately 2 percent increase following the night of sleep. Other biomarkers of Alzheimer’s disease-associated proteins were unchanged. While tau tangle formation in neurons can disrupt normal function, it is unclear what elevated blood levels of tau protein mean. Future studies are needed to elucidate this finding.

    Watch this clip featuring Dr. Matthew Walker in which he describes current research focused on identifying age-related sleep deprivation vulnerability windows for prevention of Alzheimer’s disease.

    Read more
  • High glycemic index diets may trigger insomnia www.sciencedaily.com
    Sleep Carbohydrates

    Roughly one in four women living in the United States suffers from insomnia. Lack of sleep is associated with an increased risk for car accidents and poor mental and physical health. A new study suggests that intake of high glycemic index foods may increase the risk of developing insomnia among postmenopausal women.

    Glycemic index is a value (between 0 and 100) assigned to a defined amount of a carbohydrate-containing food based on how much the food increases a person’s blood glucose level within two hours of eating, compared to eating an equivalent amount of pure glucose. Glucose has a glycemic index value of 100. Examples of high glycemic index foods include white bread, rice, potatoes, sweets, and many packaged breakfast cereals.

    The cross-sectional study was based on data collected from the Women’s Health Initiative Observational Study and included more than 50,000 postmenopausal women living in the United States who were between the ages of 50 and 79 years. In addition to providing information about their dietary intake, each of the women rated the quality of their sleep and the frequency with which they experienced certain sleep problems, including insomnia.

    The results indicated that women who ate high glycemic index diets were more likely to develop insomnia. These findings suggest that dietary modification to reduce the intake of high glycemic foods may reduce the risk of developing insomnia in postmenopausal women.

    Read more
  • A single night of sleep deprivation increased anxiety levels by 30 percent in healthy young adults. news.berkeley.edu
    Sleep Anxiety

    Nearly 40 million people living in the United States have an anxiety disorder, and many of these people report having poor or fragmented sleep. New research demonstrates that deep sleep may reduce anxiety by helping reorganize connections in the brain.

    The study involved 30 young adults whose brain activities and anxiety levels were measured after viewing stressful events following a sleep-deprived night versus a sleep-filled night. After the sleep-deprived night, the participants' anxiety levels were increased after viewing the events. When the participants had a full night of sleep, however, their anxiety levels were decreased, especially for those who experienced deep sleep.

    Brain scans demonstrated that sleep deprivation among the participants impaired the activity of the brain’s prefrontal cortex, an area that mediates the effects of stress and anxiety. Conversely, deep sleep restored prefrontal cortex function, effectively restructuring the brain to reduce anxiety.

    These findings suggest that sleep deprivation increases anxiety levels whereas deep sleep helps decrease anxiety.

    Read more
  • Waves of Fluid Bathe the Sleeping Brain, Perhaps to Clear Waste www.the-scientist.com
    Brain Alzheimer's Sleep Neurons Protein

    The glymphatic system – a vast arrangement of cerebrospinal fluid-filled cavities surrounding the small blood vessels in the brain – facilitates the removal of proteins and metabolites from the central nervous system. During sleep, these interstitial spaces increase by more than 60 percent. A new study demonstrates that large quantities of cerebrospinal fluid flow through these spaces in a rhythmic fashion during deep sleep to remove waste.

    The study involved 13 young, healthy men and women whose neuronal activity, blood levels, and cerebrospinal fluid (CSF) flow were measured during sleep. As the study subjects slept, a large wave of CSF flowed through their brains roughly every 20 seconds, preceded by changes in brain neuronal activity and blood flow.

    Poor sleep – which would impair glymphatic function – has been linked to a variety of neurodegenerative diseases. For example, disruption in deep sleep is highly pronounced in people with Alzheimer’s disease and typically precedes diagnosis.

    Glymphatic activation has also been shown to play a key role in the transport of biomarkers of traumatic brain injury (TBI). In particular, cerebrospinal fluid-mediated removal of tau protein in the brain via glymphatic routes is crucial for limiting secondary neuronal damage following traumatic brain injury. Unfortunately, some types of TBI impair glymphatic function and may be one reason why people with TBI are at a higher risk for neurodegenerative diseases.

    Taken together, these data suggest that sleep – especially deep sleep – is not only important for the prevention of Alzheimer’s disease but also may be key in the treatment of TBI.

    Read more
  • A small study found that 4 nights of sleep restriction (5hrs sleep/night) resulted in decreased satiety after a calorically dense meal. www.sciencedaily.com
    Metabolism Sleep Satiety

    A small study found that 4 nights of sleep restriction (5hrs sleep/night) resulted in decreased satiety after a calorically dense meal and altered lipid metabolism in healthy people. Catch up sleep one night only helped a little.

    This was a very small study that needs to be repeated. The preliminary results found that four consecutive nights of 5 hours of sleep per night changed lipid metabolism in healthy individuals. Lipids were cleared from the bloodstream faster after a meal but they were stored in adipose tissue. This could partially explain why people did not feel satiated after a calorically dense meal.

    Other studies have shown that sleep restriction also alters hormones that regulate satiety. Several studies have also shown that sleep restriction disrupts glucose metabolism. Many mechanisms may be at play.

    One night of catch up sleep led to some improvements but satiety and lipid metabolism were still disrupted.

    Read more
  • A mid-day nap 3x per week in children ages 10-12 was associated with a 7.6% increase in academic performance, elevated mood, improved behavior. penntoday.upenn.edu
    Brain Sleep Behavior Development

    A mid-day nap at least 3x per week in children ages 10-12 was associated with a 7.6% increase in academic performance, elevated mood, improved self-control, and fewer behavioral problems.

    This study was conducted in 3,000 school children in China where napping continues through elementary and middle school, even into adulthood. It is well known that napping is critical for intellectual development and emotional regulation in infants and toddlers so it is not too surprising that naps may be beneficial for older children as well.

    Additionally, many school children remain drowsy throughout the day as a consequence of early school start times. The authors of this study propose an interesting potential “middle ground” solution to the early start times; mid-day naps at school.

    This study was not a randomized controlled trial which is necessary to establish causation. Still, I think almost every parent would agree that naps make happier and healthier children.

    Read more
  • After exposure to daytime bright light (6.5 hours), evening use of a tablet for two hours did not affect sleep in healthy young students. www.sciencedaily.com
    Sleep Circadian Rhythm Blue Light

    Getting bright light throughout the day could be just as important for improving sleep as avoiding blue light exposure at night.

    After exposure to daytime bright light (6.5 hours), evening use of a tablet for two hours did not affect sleep in healthy young students.

    The evening tablet use did not affect sleepiness and saliva melatonin levels before sleep, nor did it change the time to fall asleep or subsequent sleep. It has previously been shown that early bright light exposure can ameliorate some of the suppressive effects of evening blue light has on melatonin levels.

    To learn more about the importance of early bright light exposure on improving sleep quality, check out my podcast with Dan Pardi that talks about a lot of interesting points relevant to this…

    https://www.foundmyfitness.com/episodes/dan-pardi

    Read more
  • A bidirectional relationship between sleep and oxidative stress in Drosophila journals.plos.org
    Sleep Stress Neurons Antioxidant

    Abstract

    Although sleep appears to be broadly conserved in animals, the physiological functions of sleep remain unclear. In this study, we sought to identify a physiological defect common to a diverse group of short-sleeping Drosophila mutants, which might provide insight into the function and regulation of sleep. We found that these short-sleeping mutants share a common phenotype of sensitivity to acute oxidative stress, exhibiting shorter survival times than controls. We further showed that increasing sleep in wild-type flies using genetic or pharmacological approaches increases survival after oxidative challenge. Moreover, reducing oxidative stress in the neurons of wild-type flies by overexpression of antioxidant genes reduces the amount of sleep. Together, these results support the hypothesis that a key function of sleep is to defend against oxidative stress and also point to a reciprocal role for reactive oxygen species (ROS) in neurons in the regulation of sleep.

    Read more
  • People that have their deep sleep cycle disrupted for one night experience a 10% increase in amyloid plaque levels. www.sciencedaily.com
    Alzheimer's Sleep Neurons Blue Light Time-Restricted Eating

    People that have their deep sleep cycle (slow-wave cycle) disrupted for one night experience a 10% increase in amyloid plaque levels compared to when their deep sleep cycle is uninterrupted.

    Amyloid beta plaques accumulate outside of neurons in the brain and disrupt synapses (the connections between two neurons that form memories) and is just one way that memory loss occurs in Alzheimer’s disease.

    This study showed that slow-wave sleep, which is the deep sleep that people need to wake up feeling rested, is important for preventing the accumulation of amyloid plaques. While a few nights of disrupted sleep is likely not a problem, it is the chronic disrupted slow-wave sleep (ie. sleep apnea) that may put a person at increased risk for Alzheimer’s disease.

    A few things that I have found improve my sleep are switching all blue lights off before sunset since blue light stops the production of melatonin. I have red lights that turn on before sunset and this has really helped my sleep pattern. Also, a bright light exposure first thing in the morning to start my circadian clock has really helped. Lastly, following a time-restricted eating pattern where I do not eat 4 hours before bed and a cold/quiet room also make a huge difference.

    My podcast with Dr. Satchin Panda discusses the importance of dark/light and food timing in sleep. Dr. Satchin Panda podcast: https://youtu.be/-R-eqJDQ2nU

    My podcast with Dan Pardi also discusses ways to optimize sleep. Dan Pardi podcast: video: https://youtu.be/VhMjrWlWhLU

    Read more
  • The reason old folk sleep less found: neurons responsible for regulating sleep patterns in "ventrolateral preoptic nucleus" die off www.huffingtonpost.com
    Brain Aging Sleep Neurons

    The method by which this area was found to be critical is particularly interesting.

    FTA:

    Saper analyzed a dataset of almost 1,000 subjects who had entered into a memory and aging study back in 1997, when they were all healthy 65-year-olds. As part of the study, they had all agreed to wear a small watch-sized device on their wrists for about 7 to 10 days, every two years, that would record all their movements. Upon their deaths, their brains were donated to science, so research could continue.

    Saper chose 45 brains to examine, based on whether or not the ventrolateral preoptic nucleus was still intact. First he stained the brain in order to find the cluster of neurons, which were located in a similar part of the human brain as the rats' brains.

    Then he linked the neurons found in the brain to the rest-activity behavior data collected in that person’s final year of life. He found that the fewer neurons one had, the more sleep fragmentation that person experienced in the last year of life. Brains with the largest amount of neurons (over 6,000) belonged to people with longer, uninterrupted sleep.

    Another key finding from the study: The link between fewer neurons and less sleep was even more pronounced in people who had died with Alzheimer’s disease.

    Read more