Sleep Duration and Biological Aging: What a Nature Study Found

Sleeping too little or too much goes with faster biological aging across the body, according to a new Nature study. The sweet spot in this data was 6.4 to 7.8 hours.^[1]

What the researchers did

Using UK Biobank participants aged 37 to 84, the team built 23 “aging clocks.” These are machine-learning models that use brain imaging, blood proteins and blood metabolites to estimate how old an organ system looks compared with the person’s calendar age. They then compared each clock’s age gap with self-reported nightly sleep.^[1]

What they found

• The pattern was U-shaped. Biological age gaps were smallest at roughly 6.4 to 7.8 hours of sleep, varying a bit by organ and sex.^[1]
• Short sleep (under 6 hours) and long sleep (over 8 hours) were each linked to higher risk of diseases beyond the brain, and to all-cause mortality, compared with 6 to 8 hours.^[1]
• For late-life depression, short sleep showed a more direct link, while the long-sleep link seemed to run partly through the aging clocks.^[1]

What this doesn’t show

Sleep was self-reported, and the study doesn’t prove that sleep length makes organs age faster. The authors note that genetic analysis doesn’t give strong evidence that disease causes the sleep pattern, but it can’t fully rule that out.^[1] Long sleep in particular may be a marker that something else is going on, not a cause of it. So don’t try to sleep your way to a younger liver by forcing more hours in bed.

What to do with it

1. Find your real average. One night means little. Note your sleep and wake times for seven days and work out the average.
2. Aim for the middle of the range. If you’re under six hours, move bedtime earlier by 15 minutes every few nights until you’re regularly near seven.
3. Don’t chase more than eight. If you’re sleeping over eight hours and still tired, or that’s a recent change, bring it to your clinician. Long sleep can travel with other health problems, so it’s worth a check.
4. Keep your schedule steady. A steady wake time, weekends included, is the easiest lever to pull.

Related reading: three health non-negotiables: sleep, strength and cardio.

References

[1] O’Toole CK, Song Z, Anagnostakis F, et al. Sleep chart of biological ageing clocks in middle and late life. Nature, 2026. Population: UK Biobank participants aged 37 to 84; self-reported sleep duration compared with 23 biological ageing clocks derived from imaging, plasma proteomics and metabolomics. DOI: https://doi.org/10.1038/s41586-026-10524-5. Finding as used: a U-shaped pattern between sleep duration and biological age gaps across brain and body systems; lowest age gaps at 6.4 to 7.8 hours, varying by organ and sex; short (<6 h) and long (>8 h) sleep versus 6-8 h associated with increased risk of systemic diseases beyond the brain and all-cause mortality; for late-life depression, short sleep showed a more direct link and ageing clocks may partially mediate the long-sleep pathway; Mendelian randomization gave no strong evidence that disease causally affects sleep but cannot completely exclude reverse causality. ↑︎

Kurt Greiner

Kurt is a digital strategist and IT professional blending emerging technology with practical application, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.