Overview
- Researchers working with the UK Biobank built 23 organ-specific ageing clocks and reported a U-shaped link between reported sleep time and organ age, with the lowest ageing profiles at roughly 6.4 to 7.8 hours.
- Both short sleep under six hours and long sleep over eight hours were linked to higher risks of disease across multiple systems and to about 40–50% higher all-cause mortality.
- The team used machine learning on MRI scans, blood proteins, and metabolites to estimate organ age, and they analyzed questionnaire sleep reports limited to 4–10 hours from a middle-to-late-life cohort.
- Genetic analyses tied short sleep to heart failure, depression, and type 2 diabetes, while long sleep showed stronger genetic links to brain and psychiatric traits, with small sex differences in optimal ranges for some organ clocks.
- The authors caution that the results show associations rather than proof of cause and effect and present the Sleep Chart to guide future intervention studies and possible public-health advice.