Sleep Duration and Mortality Risk Association
Summary
The association between habitual sleep duration and mortality risk has been investigated across epidemiological and experimental paradigms. Evidence consistently indicates a U-shaped or J-shaped relationship, in which both short and long sleep are linked to elevated all-cause mortality relative to a reference of seven to eight hours per night. Short sleep may amplify sympathetic activity, inflammatory pathways and metabolic dysregulation, whereas extended sleep may reflect underlying morbidity or inflammatory burden. These patterns have been observed in diverse populations, including community-dwelling adults, older cohorts and clinical subsamples, and have been confirmed by meta-analyses and objective assessments, underscoring global relevance. Understanding the optimal sleep window and its deviations informs public health strategies and clinical recommendations aimed at reducing premature death.
Research from Nature Portfolio
A foundational dose–response meta-analysis of cohort studies synthesised prospective data on both nocturnal and 24-hour sleep duration in over 1.5 million participants. It identified a nadir in mortality risk at approximately seven hours of sleep, with incremental risk associated with each hour below or above this optimum. The curve of risk demonstrated a steep rise beyond nine hours of nightly sleep and a more gradual increase at shorter durations. These findings reinforced the paradigm of a non-linear association between sleep and survival and provided a quantitative framework for public health guidelines.
Sleep Duration and Mortality Risk Association publication trend
The graph below shows the total number of articles in sleep duration and mortality risk association across all publications each year (not limited to Nature Index journals).
Technical terms
All-cause mortality: The total rate of death from any cause in a defined population.
Hazard ratio (HR): A measure of the relative risk of an event occurring in one group compared to another over time.
Actigraphy: The use of a wearable accelerometer to record movement and infer sleep duration and patterns objectively.
J-shaped association: A relationship in which risk decreases to a minimum at a reference point and then increases sharply beyond that point.
References
- Nighttime sleep duration, 24-hour sleep duration and risk of all-cause mortality among adults: a meta-analysis of prospective cohort studies. Scientific Reports (2016).
- Imbalanced sleep increases mortality risk by 14–34%: a meta-analysis. GeroScience (2025).
- Associations between actigraphy-measured sleep duration, continuity, and timing with mortality in the UK Biobank. Sleep (2023).
- Association of Sleep Duration With All- and Major-Cause Mortality Among Adults in Japan, China, Singapore, and Korea. JAMA Network Open (2021).
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