title: Sleep duration and risk of coronary heart disease: A systematic review and meta-analysis of prospective cohort studies.
abstract: BACKGROUND
  Epidemiological studies suggest an association between sleep duration and risk of coronary heart disease, however, the results are controversial. We conducted this systematic review and meta-analysis to summarize the potential dose-response relationship between sleep duration and risk of coronary heart disease.
  
  
  METHODS
  The electronic reference databases (PubMed and Embase) were searched through January 2016 with selection criteria for relevant studies. Both semiparametric and parametric methods were used to calculate the pooled risk estimates.
  
  
  RESULTS
  Seventeen articles with 22 independent reports involving 17,841 incident cases of coronary heart disease among 517,440 participants were included in our meta-analysis. A U-shaped relationship was detected between sleep duration and risk of coronary heart disease, with the lowest risk at 7-8h per day. Compared with 7h sleep duration per day, the combined relative risk of coronary heart disease were 1.11 (95% CI=1.05-1.16) for an reduction of 1h and 1.07 (95% CI=1.00-1.15) for an increment of 1h. And the results almost did not change in the subgroup analysis of gender and fatal cases. Exclusion of any single study did not alter the combined relative risk. In addition, visual inspection of funnel plots, Begg's and Egger's tests failed to identify publication bias.
  
  
  CONCLUSIONS
  Both short and long sleep durations are significantly associated with increased risk of coronary heart disease. Compared with 7h sleep duration per day, the risk of coronary heart disease increases 11% for an hour decrease and increases 7% for an hour increase.
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Wuhan Hospital for the Prevention and Treatment of Occupational Diseases, Wuhan, Hubei 430030, China.
authors.forename: Dongming
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Social Medicine and Health Management, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Wenzhen
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Xiuqing
authors.initials: X
authors.lastname: Cui
authors.affiliation: Department of Cardiology, Union Hospital, Tongji Medical College, Huzhong Univerisity of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Yidi
authors.initials: Y
authors.lastname: Meng
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
authors.forename: Jixuan
authors.initials: J
authors.lastname: Ma
authors.affiliation: Wuhan Hospital for the Prevention and Treatment of Occupational Diseases, Wuhan, Hubei 430030, China.
authors.forename: Guilin
authors.initials: G
authors.lastname: Yi
authors.affiliation: Department of Occupational & Environmental Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China; Key Laboratory of Environment and Health, Ministry of Education & Ministry of Environmental Protection, State Key Laboratory of Environmental Health (Incubating), School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China. Electronic address: wchen@mails.tjmu.edu.cn.
authors.forename: Weihong
authors.initials: W
authors.lastname: Chen
mesh_terms: D015331:Cohort Studies; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D006801:Humans; D064887:Observational Studies as Topic / Q000379:methods; D011446:Prospective Studies; D012307:Risk Factors; D012890:Sleep / Q000502:physiology*; D013997:Time Factors
keywords: Coronary heart disease; Sleep duration; Systematic review