A long-held belief that sleep is the best medicine is being challenged, as a new study suggests that sleeping more than eight hours a day may actually accelerate physical aging.
6 to 8 Hours Optimal; Risk Rises Further Outside the Range
According to recent research by scientists at Columbia University Irving Medical Center, an analysis of the link between sleep duration and biological aging—based on health data from about 500,000 participants in the UK Biobank—found that aging proceeded most slowly among the group that maintained 6.4 to 7.8 hours of sleep a day.
A "U-shaped" pattern emerged, in which the pace of aging accelerated again when sleep fell below six hours or exceeded eight hours. The curve is interpreted to mean that aging progresses most gently within the recommended range, while the risk of aging rises the further one moves away from that range.
The study has drawn attention because it went beyond simple self-reporting to directly track the aging status of multiple organs, including the brain, liver, lungs, immune system, skin, fat tissue and pancreas. The fact that it was based on a large cohort of up to 500,000 people was cited as supporting the study's credibility. Some assessments note that the research differs from previous sleep studies in that it comprehensively examined the aging status of various organs rather than a single specific organ.
Insufficient Sleep Linked to Cardiovascular Issues, Excessive Sleep to Brain Health
The researchers also pointed out that short sleep and long sleep affect health through different pathways. Sleep deprivation was found to increase the likelihood of cardiovascular and metabolic diseases through chronic inflammatory responses, immune dysfunction and metabolic disorders. Excessive sleep, on the other hand, was analyzed as being closely linked to deteriorating brain health, such as depression and cognitive decline.
The researchers do not rule out the possibility, however, that rather than long sleep itself directly driving aging, it may be a secondary phenomenon arising as the body responds to signs of a specific disease or health problem it already faces. This aligns with the view that a sudden increase in sleep duration should be read not as simple accumulated fatigue but as an early signal of a health problem.
Experts recommend that adults maintain around seven hours of sleep a day, and that developing the habit of going to sleep and waking up at as consistent a time as possible—including on weekdays and weekends—helps with healthy aging.
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