title: Short and long sleep durations are both associated with increased risk of stroke: a meta-analysis of observational studies.
abstract: BACKGROUND
  There is uncertainty about the relationship between sleep duration and stroke risk.
  
  
  OBJECTIVE
  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).
  
  
  CONCLUSIONS
  Both short and long sleep durations have a significant association with higher risk of stroke.
authors.affiliation: Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Internal Medicine, People's Hospital of Chibi City, Chibi, China.
authors.forename: Beihai
authors.initials: B
authors.lastname: Ge
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Guo
mesh_terms: D006801:Humans; D064887:Observational Studies as Topic; D012306:Risk; D012890:Sleep; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors
keywords: long sleep duration; meta-analysis; observational studies; short sleep duration; stroke