Too Little or Too Much Sleep Linked to Faster Biological Aging, Study Finds

A new analysis published in the journal Nature has found that sleeping too little and too much are both associated with faster biological aging in the brain, heart, lungs, immune system and other organs, and with a broad range of diseases. Study leader Junhao Wen, assistant professor of radiology at Columbia University Vagelos College of Physicians and Surgeons, said the work "goes further" than earlier research, showing sleep duration is "associated with faster aging in nearly every organ, supporting the idea that sleep is important in maintaining organ health within a coordinated brain-body network."

Scientists increasingly use "aging clocks" — machine-learning tools built from biological data such as blood-test proteins — to estimate whether a person is aging faster or slower than their chronological age. Instead of one whole-body clock, Wen's team built clocks for individual organs, using structural measurements from medical imaging, organ-specific proteins and molecules found in blood. "I'm also a light sleeper and was getting worried about the effects on myself," Wen said.

The team used data from about half a million UK Biobank participants, applying machine learning across 23 aging clocks covering 17 organ systems and comparing them with each participant's self-reported sleep duration. A clear U-shaped pattern emerged: short sleep, under 6 hours, and long sleep, over 8 hours, were both linked to faster biological aging, while the lowest aging levels were seen in people sleeping 6.4 to 7.8 hours. The findings do not show sleep duration itself causes organs to age faster or slower; researchers say it could instead be a sign of poorer health.

Short sleep was significantly associated with depressive episodes, anxiety disorders, obesity, type 2 diabetes, hypertension, ischemic heart disease and heart arrhythmias. Both short and long sleep were linked to chronic obstructive pulmonary disease (COPD) and asthma, and to digestive disorders including gastritis and gastroesophageal reflux disease (GERD). Wen said the findings show "sleep duration is a deeply embedded part of our entire physiology, with far-reaching implications across the body."

Using "mediation analysis," the researchers also examined whether biological aging helps explain the link between sleep duration and late-life depression. They could not establish causation, but found short sleep may be more directly connected to late-life depression, while long sleep may work through aging pathways in the brain and adipose, or fat, tissue. "Our study suggests there may be different biological pathways between long and short sleepers that lead to the same outcome, late-life depression, and we shouldn't treat them the same way," Wen said.