Although sleep has long been known to be critical for good health and well-being, the optimal amount of sleep that supports the body best is less clear. Researchers have recently demonstrated that sleeping either too little or too much was correlated with signs of faster aging across numerous organ systems. The authors identified a relatively tight rangeapproximately six and a half to eight hours related to the slowest pace of aging. Researchers analyzed data from over 500,000 UK Biobank participants aged from late thirties to mid-eighties.
They used innovative biological clocks derived from brain scans, blood metabolomics and proteomics to quantify aging in the brain, the heart, the lungs, the immune system, and many other organs. They found a distinct U pattern. People who claimed to sleep less than six hours or more than eight hours had higher biological age gaps than people who slept between about 6.
4 to 7.8 hours. The optimal range was a little different for various organs and for each sex, but the pattern was consistent across the body. The results have implications that go beyond age-related disease markers. Both short and long sleep duration were predictive of increased risk, independent of other variables, for many conditions: depression anxiety type 2 diabetes, high blood pressure, heart disease, chronic lung disease, acid reflux, and other digestive disorders. Risk of death from any cause also increased with both short and long sleep duration. The work points to sleep duration as an aspect of physiology, not lifestyle.
Interestingly the pathways seemed to diverge. For long sleep, biological aging clocks appeared to be a partial mediator of the link between long sleep and subsequent depression; for short sleep, the association was more direct. Although reverse causality cannot be categorically excluded (i.e.
disease causes poor sleep), the consistent findings observed across many biological systems indicate that extreme sleep duration could bring a cascade of health deterioration. Still, the only conclusion that can be made is that the idea that ‘more sleep is better’ is debunked by this study. There are individuals who may sleep more for health reasons but longer sleep is shown here to be connected to accelerated aging even when controlling for the other factors measured in the 8 different models.
The benefit of chronic short sleep is well known, and this study strengthens the evidence for this association for the whole body. How does this translate to the real world? Daily requirements–seven hours or soof sleep seems to facilitate healthier biological aging of the brain and body, with time being an important factor. Of course, duration alone isn’t everything, but having an attainable goal for many adults to strive for is quite possibly the biggest contribution of the duration findings.
Minor changes like standardizing bed time rituals or minimizing the amount of time in front of the computer screen after work may provide more people with the opportunity to secure protective sleep durations. This research contributes to the ongoing knowledge that sleep is a complex process affecting all organ systems. It is not just the restoration of the brain, but restoration of the whole body.
