title: Sleep duration and risk of stroke: a dose-response meta-analysis of prospective cohort studies.
abstract: OBJECTIVE
  Suboptimal sleep duration has been considered to increase the risk of stroke incidence. Thus we aimed to conduct a dose-response meta-analysis to examine the association between sleep duration and stroke incidence.
  
  
  METHODS
  We searched PubMed, Web of science and the Cochrane Library to identify all prospective studies evaluating the association of sleep duration and nonfatal and/or fatal stroke incidence. Then, restricted cubic spline functions and piecewise linear functions were used to evaluate the nonlinear and linear dose-response association between them.
  
  
  RESULTS
  We included a total of 16 prospective studies enrolling 528,653 participants with 12,193 stroke events. Nonlinear dose-response meta-analysis showed a J-shaped association between sleep duration and total stroke with the lowest risk observed with sleeping for 7 h. Considering people sleeping for 7 h as reference, long sleepers had a higher predicted risk of total stroke than short sleepers [the pooled risk ratios (95% confidence intervals): 4 h: 1.17 (0.99-1.38); 5 h: 1.17 (1.00-1.37); 6 h: 1.10 (1.00-1.21); 8 h: 1.17 (1.07-1.28); 9 h: 1.45 (1.23-1.70); 10 h: 1.64 (1.4-1.92); pnonlinearity<0.001]. Short sleep durations were only significantly associated with nonfatal stroke and with total stroke in the subgroups of structured interview and non-Asian countries. Additionally, we found a slightly decreased risk of ischemic stroke among short sleepers. For piecewise linear trends, compared to 7 h, every 1-h increment of sleep duration led to an increase of 13% [the pooled risk ratios (95% confidence intervals): 1.13 (1.07-1.20); p < 0.001] in risk of total stroke.
  
  
  CONCLUSIONS
  Both in nonlinear and piecewise linear dose-response meta-analyses, long sleep duration significantly increased the risk of stroke incidence.
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Qiao
authors.initials: Q
authors.lastname: He
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Wu
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Huixu
authors.initials: H
authors.lastname: Dai
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Ai
authors.affiliation: Department of Clinical Epidemiology, Institute of Cardiovascular Diseases and Center of Evidence Based Medicine, The First Affiliated Hospital, China Medical University, Shenyang, China; Center of Evidence Based Medicine, Liaoning Province & China Medical University, Shenyang, China. Electronic address: sjp562013@126.com.
authors.forename: Jingpu
authors.initials: J
authors.lastname: Shi
mesh_terms: D015331:Cohort Studies; D006801:Humans; D015994:Incidence; D011446:Prospective Studies; D012307:Risk Factors; D012890:Sleep; D020521:Stroke / Q000453:epidemiology*; D013997:Time Factors
keywords: Meta-analysis; Prospective studies; Sleep duration; Stroke