Relationship of Sleep Duration With All-Cause Mortality and Cardiovascular Events: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.

Background-Effects of extreme sleep duration on risk of mortality and cardiovascular outcomes remain controversial. We aimed to quantify the dose-response relationships of sleep duration with risk of all-cause mortality, total cardiovascular disease, coronary heart disease, and stroke. Methods and Results-PubMed and Embase were systematically searched for prospective cohort studies published before December 1, 2016, that examined the associations between sleep duration and at least 1 of the 4 outcomes in generally healthy populations. U-shaped associations were indicated between sleep duration and risk of all outcomes, with the lowest risk observed for approximate to 7-hour sleep duration per day, which was varied little by sex. For all-cause mortality, when sleep duration was <7 hours per day, the pooled relative risk (RR) was 1.06 (95% CI, 1.04-1.07) per 1-hour reduction; when sleep duration was >7 hours per day, the pooled RR was 1.13 (95% CI, 1.11-1.15) per 1-hour increment. For total cardiovascular disease, the pooled RR was 1.06 (95% CI, 1.03-1.08) per 1-hour reduction and 1.12 (95% CI, 1.08-1.16) per 1-hour increment of sleep duration. For coronary heart disease, the pooled RR was 1.07 (95% CI, 1.03-1.12) per 1-hour reduction and 1.05 (95% CI, 1.00-1.10) per 1-hour increment of sleep duration. For stroke, the pooled RR was 1.05 (95% CI, 1.01-1.09) per 1-hour reduction and 1.18 (95% CI, 1.14-1.21) per 1-hour increment of sleep duration. Conclusions-Our findings indicate that both short and long sleep duration is associated with an increased risk of all-cause mortality and cardiovascular events.