Short and Long Sleep Durations are Both Associated with Increased Risk of Stroke: A Meta-Analysis of Observational Studies

BACKGROUND: There is uncertainty about the relationship between sleep duration and stroke risk. AIM: We aimed to clarify the relationship between sleep duration and risk of stroke by using epidemiological evidence. METHODS: We searched MEDLINE and EMBASE to identify all studies that might be looking at the association between sleep duration and stroke, including both cohort and cross-sectional studies. Pooled hazard ratios (HRs) and odds ratios (ORs) were calculated through a random-effects model. RESULTS: Our study included a total of 12 cohort studies and 6 cross-sectional studies. Pooled results from the cohort studies showed that short sleep duration was associated with a higher risk for stroke [HR, 1.13; 95% confidence interval (CI) 1.02-1.25], and that long sleep duration also increases the risk of having a stroke (HR, 1.40; 95% CI, 1.16-1.64). Results from cross-sectional studies confirmed the relationship between stroke and inappropriate sleep duration, either too little sleep or too much. For short sleep duration, the OR was 1.71 (1.39-2.02); for long sleep duration, the OR was 2.12 (1.51-2.73). CONCLUSION: Both short and long sleep durations have a significant association with higher risk of stroke.