Forget eight hours: Huge UK study reveals the real sleep sweet spot for slowing ageing
Key Points
- A Nature study of 500,000 UK Biobank participants identifies the optimal sleep duration for slowing biological ageing at 6.4 to 7.8 hours a night.
- Both short sleep (under 6 hours) and long sleep (over 8 hours) accelerate ageing across 17 organ systems, with short sleepers facing 50% higher mortality and long sleepers 40%.
- The sweet spot varies by organ and sex; the brain proteomic clock favours 7.7 to 7.8 hours, while the brain MRI clock bottoms out at 6.5 hours.
- Abnormal sleep duration links to 153 systemic diseases including heart disease, type 2 diabetes, depression and ADHD.
- Short sleep relates directly to late-life depression; long sleep contributes indirectly through accelerated brain and adipose ageing.
A new analysis of half a million UK Biobank participants has pinpointed the precise sleep window that slows biological ageing to between 6.4 and 7.8 hours a night.
The Columbia University-led study, published in Nature on 13 May, tracked 23 biological ageing clocks across 17 organ systems using brain imaging, plasma proteomics and metabolomics data from participants aged 37 to 84.
Researchers identified a consistent U-shaped pattern in which both short sleep (under 6 hours) and long sleep (over 8 hours) were linked to accelerated ageing across the brain, lungs, liver, immune system, skin, endocrine system, adipose tissue and pancreas.
The sweet spot varied by organ and sex, with the brain proteomic clock showing minimum ageing at 7.7 hours for women and 7.8 hours for men, while the brain MRI clock bottomed out closer to 6.5 hours.
Mortality risk increased sharply at both ends of the curve. Short sleepers faced a 50% higher risk of all-cause death compared with those getting 6 to 8 hours, while long sleepers faced a 40% higher risk.
The analysis identified 153 systemic diseases linked to abnormal sleep duration, spanning cardiovascular conditions including ischaemic heart disease and hypertension, metabolic disorders such as type 2 diabetes and obesity, psychiatric conditions including depression and anxiety, and pulmonary and digestive diseases.
Short sleep showed the broader systemic footprint, while long sleep correlated more strongly with brain-related conditions including schizophrenia, bipolar disorder, ADHD and major depressive disorder.
“Our study goes further and shows that too little and too much sleep are associated with faster ageing in nearly every organ, supporting the idea that sleep is important in maintaining organ health within a coordinated brain-body network, including metabolic balance and a healthy immune system,” said Junhao Wen, Assistant Professor of Radiology at Columbia University Vagelos College of Physicians and Surgeons.
The researchers also examined late-life depression and found that short and long sleep contributed through different mechanisms.
Short sleep showed a direct link to depression, while long sleep operated indirectly through accelerated ageing in the brain and adipose tissue, with the brain ageing clock alone accounting for 62% of the total effect.
The study relied on self-reported sleep duration collected at baseline rather than wearable or laboratory measures, and the authors note that longitudinal follow-up and more diverse populations are needed to confirm causality.
