Study Links 6–8 Hours of Sleep to Lower Risk of Dozens of Diseases

A large-scale observational study has associated sleeping between six and eight hours per night with reduced risk for numerous diseases. In contrast, sleeping fewer than five hours was tied to higher likelihood of developing multiple health conditions.

The research appeared in the journal PLOS Medicine. It was led by Shengchi Sun of Capital Medical University in China and colleagues, drawing on data from 95,559 participants enrolled in the UK Biobank.

Researchers tracked participants over an average follow-up period of 8.9 years. At baseline, each wore a wrist-worn device continuously for seven days and nights to objectively measure sleep duration, sleep stages—including deep sleep and rapid eye movement (REM) sleep—as well as sleep regularity and nighttime awakenings.

REM and deep sleep durations tied to disease risk

The team observed that longer REM sleep duration correlated with lower risk for 83 distinct diseases, including heart failure, dementia, and Parkinson’s disease. Longer deep sleep duration was associated with reduced risk for seven health conditions, among them type 2 diabetes and major depressive disorder.

Irregular sleep and nighttime awakenings raise risks

Conversely, irregular sleep patterns and increased time spent awake after falling asleep were linked to higher risk for several disorders, including anxiety disorders and alcohol- and drug-related conditions.

Sleep duration thresholds show clear risk gradients

Participants who slept less than five hours per night faced elevated risk for 37 diseases. Meanwhile, those reporting six to eight hours of nightly sleep exhibited the lowest risk levels across a broad range of illnesses.

The authors emphasized that the study identifies statistical associations—not causal relationships—between sleep patterns and health outcomes. Because it relied on observational data rather than controlled clinical trials, the findings do not demonstrate that sleep habits directly cause or prevent disease.

Nonetheless, the researchers stated the results reinforce the importance of sufficient and consistent sleep, and suggest potential protective roles for specific sleep stages in maintaining long-term health.