Sleep is one of the most basic human needs, yet millions of people around the world struggle to get healthy sleep every night.
Some people sleep only a few hours because of stress, work, or health problems, while others sleep much longer than average and still feel tired.
Scientists have long known that poor sleep is linked to health problems such as obesity, heart disease, diabetes, memory issues, and depression. But a new study suggests sleep may affect the body in an even deeper way than researchers previously understood.
According to new research from Columbia University, both too little sleep and too much sleep may be linked to faster aging throughout the body. The findings suggest that sleep habits are connected not only to brain health but also to aging in the heart, lungs, immune system, and many other organs.
The study was led by Dr. Junhao Wen, assistant professor of radiology at Columbia University Vagelos College of Physicians and Surgeons, and was published in the journal Nature.
The researchers used a modern scientific tool known as an “aging clock.” Aging clocks are becoming increasingly popular in medical research because they attempt to measure a person’s biological age instead of simply counting the number of years they have lived.
Two people may both be 60 years old, for example, but one person’s organs may function more like those of a younger person while the other person’s body may show signs of accelerated aging.
Scientists create aging clocks using artificial intelligence and machine learning. These systems study large amounts of biological information such as proteins in the blood, medical scans, and metabolic markers.
By analyzing these patterns, researchers can estimate whether organs appear biologically older or younger than expected.
Most previous aging clocks focused on the body as a whole. However, Dr. Wen’s team developed separate aging clocks for different organs. This allowed them to study whether sleep affected some organs more strongly than others.
The researchers used data from nearly half a million people enrolled in the UK Biobank, one of the world’s largest medical research databases. They analyzed information from 23 aging clocks covering 17 organ systems throughout the body.
The scientists examined how sleep duration reported by participants related to signs of aging in different organs. A very clear pattern appeared.
People who reported sleeping fewer than six hours per night tended to show faster aging in many organs. Surprisingly, people who regularly slept more than eight hours also showed signs of accelerated aging. The healthiest aging patterns were seen in people who slept between about 6.4 and 7.8 hours each night.
The researchers described this as a “U-shaped” pattern because both very short and very long sleep were linked to worse outcomes, while moderate sleep was associated with healthier aging.
Importantly, the study does not prove that sleep alone directly causes organs to age faster. Instead, the results suggest that abnormal sleep duration may reflect deeper health problems affecting the body.
The researchers found strong links between sleep duration and many diseases. Short sleep was associated with depression, anxiety, obesity, type 2 diabetes, high blood pressure, irregular heart rhythms, and heart disease.
Both short and long sleep were linked to lung diseases such as asthma and chronic obstructive pulmonary disease, as well as digestive disorders including acid reflux and gastritis.
The study also explored how sleep may be connected to late-life depression. The researchers used special statistical methods to study whether aging in certain organs might help explain the relationship between sleep and depression in older adults.
Their findings suggested that short sleep and long sleep may affect depression through different biological pathways. Short sleep appeared to have a more direct connection to depression itself, while long sleep may work indirectly through changes in the brain and body fat tissue.
Dr. Wen said this discovery could become important for future treatments because people with different sleep problems may need different medical approaches.
The research also highlights how deeply connected the brain and body are. Sleep is not simply a resting period for the brain. Instead, it appears to influence many systems throughout the entire body, including metabolism, inflammation, immune function, and organ health.
Scientists believe these findings may eventually help doctors better identify people at risk for disease earlier in life. Aging clocks may also help researchers study whether improving sleep habits can slow biological aging over time.
Still, the researchers caution that the study has important limitations. Sleep duration was based on self-reported information rather than direct sleep measurements.
In addition, the research shows associations rather than direct cause-and-effect relationships. It remains possible that underlying illnesses may influence sleep patterns instead of sleep causing disease.
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Source: Columbia University.
