Short sleep duration and health outcomes: a systematic review, meta-analysis, and meta-regression.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of prospective cohort studies
PubMed 27743803 · doi:10.1016/j.sleep.2016.08.006
What was done
A systematic review, meta-analysis, and meta-regression of prospective cohort studies with follow-ups of at least one year evaluated associations between short sleep duration and health outcomes compared to normal sleep. Primary outcomes included all-cause mortality and incident health conditions (diabetes mellitus, hypertension, cardiovascular diseases, stroke, coronary heart disease, obesity, depression, and dyslipidemia). Adjusted risk ratios (RRs) were pooled across studies, and meta-regression was used to assess dose-response patterns.
What was found
Data from 153 studies comprising 5,172,710 participants were included. Short sleep was significantly associated with higher risks of mortality (RR 1.12, 95% CI 1.08–1.16), diabetes mellitus (RR 1.37, 95% CI 1.22–1.53), hypertension (RR 1.17, 95% CI 1.09–1.26), cardiovascular diseases (RR 1.16, 95% CI 1.10–1.23), coronary heart disease (RR 1.26, 95% CI 1.15–1.38), and obesity (RR 1.38, 95% CI 1.25–1.53). Meta-regression showed a statistically significant linear increase in mortality for sleep duration under six hours, but no dose-response was identified for other outcomes. There was insufficient data for meta-analyses on depression and dyslipidemia.
Why it matters
This large-scale synthesis confirms that short sleep duration is consistently tied to increased risks of all-cause mortality and major cardiometabolic conditions, highlighting sleep duration below six hours as a key risk threshold.
Limits
All analyzed studies were observational prospective cohorts, precluding direct causal inference and leaving open residual confounding. Data were insufficient to meta-analyze depression or dyslipidemia, no stroke-specific effect estimates are provided in the abstract, and baseline sleep duration assessments are typically reliant on self-report.
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