We are all familiar with Sleep Number Mattress commercials telling us to find our perfect number. But it turns out scientists may have found the universal sleep number.
While conventional wisdom always said more sleep is better, more recent research has found that there can be too much of a good thing. Looking at brain imaging, blood proteins and metabolic markers, researchers examined how old cells and organs were biologically in volunteers. They found a U-shaped curve in health data. People getting less than six hours or more than eight were biologically older than their calendar age. The people doing the best were getting between 6.4 and 7.8 hours of sleep.
The researchers found that sleep impacts many organs in the body. Older research mostly focused on how sleep affects the brain. This research found that sleep also impacts the liver, immune system, skin, lungs, adipose tissue, pancreas and endocrine system. This shows that sleep isn’t just a neurological activity; it’s embedded in organ and metabolic health.
“Sleep is fundamental for healthy aging and longevity. More importantly, it is potentially modifiable,” said lead study author Dr. Junhao Wen, assistant professor of radiological sciences at Columbia Univ.
The perfect amount of sleep varies between men and women. Women’s perfect range is 6.5 to 7.8 hours, while men do best with 6.4 to 7.7. Men and women have different hormones and biological needs.
Too little sleep and too much sleep were associated with different but equally serious health concerns. Too little sleep was linked to depression, anxiety, obesity, blood sugar concerns, hypertension and heart health concerns. Too much sleep is linked to COPD, asthma and GI disorders, including GERD and gastritis.
“Short sleep is often more associated with stress of a busy lifestyle, and anxiety. It can lead to elevated blood pressure, cortisol and blood glucose levels, which all have detrimental effects over time,” said Dr. Alex Dimitriu, a double board-certified psychiatry and sleep medicine specialist. “Longer sleep is associated with depression, but more so [with] illness of the body. People who are sick or unhealthy may thus require more sleep than eight hours per night. For long sleepers, it is more likely that illness causes longer sleep, rather than longer sleep causing illness.” Dr. Dimitriu wasn’t involved in the study.
Researchers tried to minimize the possibility of reverse causality, wherein health problems would be causing changes in sleep duration rather than sleep duration causing health issues. But it’s impossible to rule out completely, as poor sleep may cause biological aging, and the health problems believed to be caused by poor sleep cause the same changes.
