Older adults and neonates have blunted circadian rhythms that markedly reduce the duration and quality of their sleep. Artificially modulating those rhythms through modification of light exposure can normalize circadian rhythms and improve cognitive performance in older adults and oxygen saturation and weight gain in infants. In this clip, Dr. Matthew Walker explains how altering light-dark schedules can improve health outcomes in older adults and babies.
Matt: There is. So what happens with age is that your circadian rhythm that we've spoke about before...I'm just going to...So your circadian rhythm that we spoke about before, which in healthy people is nice and high and peaking during the day, lots of activity, and then drops down at night, lots of inactivity, lots of deep sleep, that sinusoidal wave starts to flatten out as if someone has compressed it as we get older. So our circadian rhythm gets weaker. So we get we feel sleepier during the day and not as alert as we used to do, but we don't feel as though we are as sleepy at night. We're more awake at night because our circadian rhythm is blunted.
And so I think that's another area for aging intervention, is how can we modulate the circadian rhythm. And it turns out that it comes back to light. So one of my colleagues in the Netherlands, Eus Van Someren, did a great study where he installed circadian-regulating light in an elderly care home, you know, in a home where you care for the elderly. And many of them had cognitive decline. And he's now done some of these studies with people in with Alzheimer's disease in some of these care homes.
And when you start to create appropriate lighting in the internal environment in these homes, which if you go into them, and I used to go into them all the time during my PhD, these sort of care homes, and I would be testing my patients and seeing my patients there, they were grim environments with dim light. And these patients never got outside. They rarely had a window. And Eus Van Someren, the scientist in the Netherlands, he was able to really produce this strong bout of light during the day inside the care home and then drop out that light in the evening. And he regularized their light. And he improved the circadian rhythm. And he improved cognitive outcome measures.
Matt: Cognition got better in these Alzheimer's patients.
Rhonda: That's cool.
Matt: Now you can look at that same manipulation, that same lighting hack, at the beginning of life. So in the neonatal intensive care unit, what we used to have when we'd go in there, you just have constant light on all of the time, dim light on 24 hours a day, which prevented those infants getting the signal of a regulating 24-hour light-dark cycle.
If you regularized light in the neonatal intensive care unit, so light during the day, darkness at night, in these studies, what you see is basically almost a 50% to 60% increase in oxygen saturation within the blood of these neonates in the intensive care unit. Weight gain increases dramatically. And they end up exiting the neonatal intensive care unit at about five weeks earlier than they would otherwise.
Circadian regulation of sleep leads to better health outcomes. It does so in neonates. It does so in the elderly. So I think there is all manner of sleep possible interventions that we can think about across the lifespan when it comes to modifying disease risk at any stage of life.
A neurodegenerative disorder characterized by progressive memory loss, spatial disorientation, cognitive dysfunction, and behavioral changes. The pathological hallmarks of Alzheimer's disease include amyloid-beta plaques, tau tangles, and reduced brain glucose uptake. Most cases of Alzheimer's disease do not run in families and are described as "sporadic." The primary risk factor for sporadic Alzheimer's disease is aging, with prevalence roughly doubling every five years after age 65. Roughly one-third of people aged 85 and older have Alzheimer's. The major genetic risk factor for Alzheimer's is a variant in the apolipoprotein E (APOE) gene called APOE4.
The body’s 24-hour cycles of biological, hormonal, and behavioral patterns. Circadian rhythms modulate a wide array of physiological processes, including the body’s production of hormones that regulate sleep, hunger, metabolism, and others, ultimately influencing body weight, performance, and susceptibility to disease. As much as 80 percent of gene expression in mammals is under circadian control, including genes in the brain, liver, and muscle. Consequently, circadian rhythmicity may have profound implications for human healthspan.
Learn more about the advantages of a premium membership by clicking below.
Every other week premium members receive a special edition newsletter that summarizes all of the latest healthspan research.