A study in Nature overturns the assumption that longer sleep is universally better for aging. The research instead shows that both insufficient and excessive sleep speed up biological aging, whereas moderate sleep durations best protect cellular and organ function.
The analysis drew on UK Biobank data, examining sleep length against 23 biological aging clocks—metrics from brain imaging, blood proteins, and metabolic readings. The data formed a U-shaped trend: individuals sleeping fewer than 6 hours or more than 8 hours exhibited greater mismatches between biological and chronological age. The smallest aging gaps appeared in those averaging 6.4 to 7.8 hours of sleep, though the optimal range varied slightly depending on the organ system studied.
This challenges the idea that additional rest automatically improves health outcomes. The findings demonstrate that sleep influences aging broadly, impacting not only the brain but also the cardiovascular system, immune response, and metabolic processes. Prior studies had emphasized sleep’s role in brain aging, but this work highlights how poor sleep accelerates decline across multiple body systems.
Sleep requirements also differ between sexes. The study identified separate ideal ranges for men and women based on nine key aging clocks. Women displayed higher brain protein aging markers, while men showed greater brain MRI-based aging indicators. These distinctions likely arise from sex-specific hormonal regulation, immune activity, and metabolic needs.
The research further separates the risks tied to short versus long sleep. Sleeping less than 6 hours correlated with a broad spectrum of systemic diseases, including cardiovascular, metabolic, and psychiatric disorders. In contrast, sleeping more than 8 hours was primarily linked to brain-related conditions such as depression, schizophrenia, and bipolar disorder. The researchers suggest that prolonged sleep may not directly cause these issues but could instead reflect deeper health problems, such as accelerated brain and fat tissue aging, that remain undetected.
The study is based on UK Biobank participants aged 40 to 69, and the findings may not fully apply to younger or older populations.