A large study has revealed that sleeping less than five hours a night is associated with a higher risk of 37 diseases among nearly 100,000 adults tracked for almost nine years. The research, which involved participants from the UK Biobank, found that both the duration and structure of sleep are related to long-term health.

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Participants, totaling 95,559, wore wrist accelerometers for seven days and nights to measure various sleep stages, including REM and deep sleep. The findings indicated that increased REM sleep was linked to lower rates of numerous diseases. Specifically, for every additional 47.6 minutes of REM sleep, there was a 26 percent reduction in the rate of heart failure, a 46 percent reduction in the rate of dementia, and an 80 percent reduction in the rate of Parkinson’s disease.

Conversely, greater sleep irregularity and increased wakefulness after falling asleep correlated with heightened risks of anxiety and substance use disorders. While the study establishes relationships between sleep and health outcomes, it does not prove direct causality.

The analysis showed a nonlinear relationship between total sleep time and health outcomes, with the lowest disease risk concentrated in the six to eight-hour sleep window. Those who averaged less than five hours of sleep exhibited significant vulnerability across 37 different conditions. In total, researchers identified 156 significant associations between sleep patterns and newly diagnosed diseases after accounting for various comparisons.

The study utilized objective data, which provides clearer insights compared to self-reported sleep estimates that often differ from actual sleep patterns. Participants were followed for a median of 8.9 years, and their health records were analyzed in relation to over 1,000 disease outcomes.

The authors concluded that a recommended sleep duration for middle-aged and older adults is approximately six to eight hours, supporting the idea that this range helps safeguard against multiple health issues. They emphasized the importance of both the quantity and quality of sleep in promoting health and preventing illness.

This study was conducted by Jingsong Luo and colleagues and published on September 17, 2026, in PLOS Medicine. Funding was provided by institutions including the National Natural Science Foundation of China and the Beijing Municipal Science and Technology Commission.