Cortisol
Episodes
Derek from More Plates More Dates joins Dr. Rhonda Patrick to discuss testosterone optimization.
In this clip, Dr. Andrew Huberman discusses the benefits of morning sunlight for sleep, timing, alternatives, and managing light exposure to optimize health.
In this clip, Dr. Rhonda Patrick discusses how stress, sleep, noise, and exercise affect magnesium levels.
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Derek from More Plates More Dates joins Dr. Rhonda Patrick to discuss testosterone optimization.
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In this clip, Dr. Andrew Huberman discusses the benefits of morning sunlight for sleep, timing, alternatives, and managing light exposure to optimize health.
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In this clip, Dr. Rhonda Patrick discusses how stress, sleep, noise, and exercise affect magnesium levels.
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In this clip, Dr. Martin Gibala delves into the nuances of sex-based differences in exercise response and their implications for individual outcomes.
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Dr. Martin Gibala discusses HIIT's health benefits and describes common HIIT protocols.
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In this clip, Dr. Matthew Walker explains how altering the timing and duration of daytime light exposure influences sleep.
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Chronic stress impacts our mental and physical health. Stress increases levels of hormones like adrenaline and cortisol, which in turn, can increase a person...
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Dr. Rhonda Patrick describes how bright light exposure drives cortisol release.
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Dr. Matthew Walker discusses how anxiety affects sleep and identifies ways to manage that stress to improve sleep.
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Dr. Matthew Walker explains how altering the timing and duration of daytime light exposure influences sleep.
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Dr. Aubrey de Grey discusses technologies that can repair the various types of damage that occur during the aging process.
Topic Pages
News & Publications
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Hydration is often emphasized during exercise or heat, but daily fluid intake may also quietly shape how the body responds to stress. In a new study, researchers tested whether adults who regularly drink less show a stronger spike in cortisol during challenging situations.
The scientists studied 32 healthy adults aged 18 to 35. Half habitually drank low amounts of fluid (1.3 liters per day), while the other half drank well above average (4.4 liters per day). Over seven days, participants maintained their usual fluid intake, verified using smart bottles. Afterward, they completed a simulated job interview and a mental math challenge known to raise stress levels. The team then measured cortisol in saliva and used several hydration markers.
Although both groups showed similar increases in heart rate and self-reported anxiety, their cortisol responses diverged:
- People with low daily fluid intake had more concentrated urine, darker urine color, and higher levels of copeptin, a blood marker that reflects how hard the body is working to conserve water.
- Only the low-intake group had a clear rise in cortisol following the stress test, with hormone levels elevated at 10, 20, and 30 minutes afterward.
- Among participants whose cortisol rose meaningfully, those with lower fluid intake had a larger increase than their high‑intake counterparts.
- People with more concentrated urine across several days before the test also had stronger cortisol responses, indicating that hydration status over several days predicted reactivity.
- A simple morning urine color check helped identify who would have a stronger reaction. Those with darker urine showed larger cortisol increases.
This difference likely stems from how water-regulating hormones interact with stress systems. Vasopressin, which helps the body conserve water, also prompts the release of cortisol through a brain-to-adrenal gland signaling route called the hypothalamic-pituitary-adrenal axis. People who drink less show higher copeptin levels , consistent with stronger vasopressin activity, which may help explain their larger hormonal response under pressure.
The results suggest that hydration status shapes stress hormone responses, even when the stressful event and emotional reactions are similar. Randomized trials are now needed to test whether increasing fluid intake can reduce excessive cortisol responses and improve stress resilience.
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Childhood obesity is a growing concern with multiple contributing factors, and perhaps, exposure to artificial light at night is among the most important. To investigate this, researchers in China followed more than 218,000 schoolchildren over a 15-year period.
Each year, the students underwent health examinations that included body mass index measurements. At the same time, satellite data provided yearly measurements of how bright the outdoor night sky was in the area around each school. Children were then grouped based on long-term trends over the study period: areas that stayed consistently bright, areas that brightened slowly, areas that brightened rapidly, and areas where brightness declined. Because the rapidly brightening pattern had the lowest baseline light, it served as the reference group for all comparisons.
The study revealed distinct differences across the light exposure groups:
- Children attending schools in areas that stayed consistently bright had the highest risk. Boys had a 67% higher rate of becoming overweight or obese, and girls had a 56% higher rate.
- In areas that brightened slowly, the risk was elevated but not statistically significant.
- Areas where brightness declined showed no meaningful difference from the reference.
- Among children who began at a normal or low weight, the consistently bright group recorded 9.95 new cases of overweight or obesity per 1,000 person-years, compared with 6.10 in the rapidly brightening group and 8.04 in the slowly brightening group.
- On a population level, long-term exposure to consistently bright night-time environments accounted for about 40 percent of the risk in boys and 36 percent in girls.
Prolonged exposure to artificial light disrupts circadian rhythms, the internal clocks that regulate daily cycles of hormones such as melatonin and cortisol. When these rhythms are disturbed, appetite, metabolism, and fat storage can be affected in ways that promote weight gain. Another possible mechanism may involve brown fat, a tissue that normally burns energy to generate heat but may become less active under constant night-time light. The differences between boys and girls may reflect a mix of biological sensitivity and behavioral factors such as screen use. Finally, the stronger risks in the consistently bright and slowly brightening groups may point to the impact of longer cumulative exposure, whereas more recent increases in brightness, as in the rapidly brightening group, may not have had the same effect.
Conclusion:
Children who attended schools in brighter night-time environments were more likely to gain excess weight over the school years. The study was limited because light levels were estimated from school locations, not individual homes, and detailed information on diet, activity, or puberty was unavailable. Moreover, while the analysis adjusted for broad regional differences, it cannot be ruled out that environmental and socioeconomic changes occurring alongside rising night-time light influenced the results. Still, the findings highlight night-time light as a potential and under-recognized factor in childhood overweight and obesity. Learn more about how to improve sleep in episode #45 featuring Dr. Matthew Walker. -
Sleep loss and lower sleep duration may be associated with lower morning, afternoon and 24-h testosterone levels. (2022) link.springer.com
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.
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Prenatal choline supplementation may reduce mental illness risk in children born to Black mothers. www.eurekalert.org
Choline, a phospholipid compound present in a wide range of foods, is an essential nutrient that plays critical roles in building cell membranes and producing the neurotransmitter acetylcholine. Previous research indicates that supplemental prenatal choline improves cognitive ability, attention, and social behavior in children up to seven years of age. A pair of papers published this year explores the effects of prenatal choline supplementation on pregnancy outcomes and neuropsychiatric disease risk in Black Americans.
Neuropsychiatric diseases – commonly referred to as mental illnesses – impair the ability of affected persons to learn and work, imposing an immense burden on society. Physiological alterations that drive neuropsychiatric diseases impair normal brain function, emotion, and mood, and can arise from both genetic factors and environmental factors present before and after birth. One of the physiological alterations commonly observed with neuropsychiatric diseases is impaired suppression of irrelevant environmental mental stimuli, contributing to low mood, poor cognitive functioning, and sensory sensitivities.
Maternal stressors during pregnancy, including nutritional deficiencies, are associated with an increased risk of neuropsychiatric diseases such as schizophrenia, attention deficit disorder, and autism. Epidemiological research has revealed systemic health disparities that contribute to poorer health outcomes for Black Americans, including higher rates of neuropsychiatric diseases. Nutritional interventions may be effective in preventing and treating neuropsychiatric diseases by promoting healthy brain physiology.
The investigators collected data from two observational studies and a randomized clinical trial. In the first observational study, the investigators collected data from 183 pregnant females of varying ethnic identities from the United States at 14 to 16 weeks' gestation. In a second observational study, the investigators collected data from 166 pregnant females from rural Uganda at 18 to 25 weeks' gestation. Finally, in a randomized trial of choline supplementation, 100 pregnant females consumed 3,600 milligrams of choline each morning and 2,700 milligrams each night from week 16 of gestation until delivery. For each study, the investigators measured plasma concentrations of choline and the stress hormone cortisol; maternal mood and stressors; newborn P50 recording; and infant and childhood behavior measures.
Black American females had lower plasma choline concentrations at 16 weeks’ gestation compared to white American females and rural Ugandan females. These lower choline levels were associated with higher maternal concentrations of cortisol and with shorter gestation and decreased P50 inhibition, which both indicate immature neural development at birth. At three months of age, infants born to Black American mothers who had lower gestational choline presented with decreased attention and relation to caregivers, a risk factor for mental illness.
These findings suggest that the cognitive and behavioral deficits associated with lower prenatal choline may predispose children born to Black American mothers to later neuropsychiatric diseases. Prenatal choline or phosphatidylcholine supplementation may reduce disease risk.
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The effect of acute sleep deprivation on skeletal muscle protein synthesis and the hormonal environment www.ncbi.nlm.nih.gov
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.
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Ashwagandha root extract boosts stress resistance. www.ncbi.nlm.nih.gov
Emotional stressors can become overwhelming, potentially setting in motion a cascade of hormonal and physiological responses that are deleterious to a person’s mental and physical health. Evidence suggests that prolonged exposure to emotional stressors increases a person’s risk of developing cardiovascular disease, metabolic dysfunction, and depression. Findings from a recent study demonstrate that Ashwagandha root extract enhances a person’s capacity to handle stress.
Commonly referred to as winter cherry, Indian ginseng, or poison gooseberry, Ashwagandha is an herbaceous plant from the Solanaceae family. Evidence indicates that Ashwagandha exerts anti-inflammatory and neuroprotective effects. Ashwagandha has a long history of use in Ayurvedic medicine and is widely described as an adaptogen.
Adaptogens are medicinal plants that promote stress resistance, concentration, performance and endurance. They function by switching on the activity of cellular protective mechanisms, including the activation of heat shock proteins.
The prospective, double-blind, randomized, placebo-controlled trial involved 64 adults between the ages of 18 and 54 years. Each of the participants had reported a history of chronic stress but had no psychiatric problems. Half of the participants took a placebo, while the other half took a supplement containing 300 milligrams of high-concentration full-spectrum Ashwagandha extract for 60 days. The authors of the study measured the participants' serum cortisol (a stress hormone) and scored their stress levels via questionnaires before and after the intervention.
At the beginning of the study, the two groups' stress level scores were very similar. At the end of the 60-day intervention, however, the groups' average stress scores were considerably different. In particular, the difference in the participants' scores indicating symptoms of severe depression differed by 89 percent between the two groups, with the placebo group reporting worsened symptoms of depression. The participants' cortisol levels decreased nearly 28 percent from baseline in the group that took Ashwagandha. Cortisol levels in the placebo group only dropped about 8 percent.
These findings suggest that Ashwagandha root extract improves stress resistance and decreases stress biomarkers. Interestingly, meditation exerts similar effects. Listen to this episode in which Dr. Rhonda Patrick describes how meditation buffers the negative effects of stress.
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Large doses of vitamin C might mitigate the body's stress response, thereby improving immunity. www.sciencedaily.com
The human body responds to mental stress by releasing hormones called corticosteroids, triggering the body’s fight or flight response. Chronic activation of these hormones can impair immune function, increasing susceptibility to infection and disease. Findings from an early study in mice demonstrate that vitamin C mitigates the body’s stress response, thereby improving immunity.
The authors of the study immobilized mice for an hour every day for three weeks to induce stress. They also fed the mice 200 milligrams of vitamin C daily – roughly equivalent to several grams per day in humans. A control group of mice also received vitamin C but they were not subjected to stress.
The stressed mice that received large doses of vitamin C in their diets exhibited fewer signs of stress as evidenced by lower levels of corticosteroid hormones as well as other physical manifestations, such as weight loss. The mice also exhibited higher levels of IgG, the most abundant antibody in circulation, responsible for binding a broad selection of pathogens, including viruses, bacteria, and fungi, to prevent infection. Interestingly, the non-stressed mice that received large doses of vitamin C exhibited even greater increases in IgG, suggesting that stress cancels out some of the beneficial effects of the vitamin.
These findings suggest that high dose vitamin C might improve immune function, especially during times of mental and physical stress.