title: Associations between insomnia, sleep duration and poor work ability.
abstract: OBJECTIVE
  The aim of this study was to examine the independent and joint effect of insomnia and objective sleep duration on poor work ability.
  
  
  METHODS
  In this cross-sectional study, a total of 2820 Chinese manufacturing workers were categorized as insomnia patients and individuals with normal sleeping pattern by interview according to DSM-IV criteria. Sleep duration was classified into four categories: ≥7h, 6-7h, 5-6h, and <5h according to objective sleep duration of Watch-PAT-200 test. Work ability was assessed using the Chinese Work Ability Index (WAI) questionnaire. Regression analysis examined the independent and joint association of sleep duration and insomnia with poor work ability, after adjusting for various confounding factors.
  
  
  RESULTS
  Insomnia and objective short sleep duration were both independently associated with poor work ability. Compared with the normal sleeping and ≥7h sleep duration group, the highest risk of poor work ability was in the insomnia patients with <5h sleep duration [odds ratio (OR) 3.43, 95% confidence interval (CI) 1.87-5.23], followed by the individuals with insomnia who slept 5-6h (OR 2.03, 95% CI 1.42-2.67).
  
  
  CONCLUSIONS
  Insomnia and sleep duration in workers are both separately and together associated with increased risk of poor work ability. Objective sleep duration should be taken into consideration when assessing the work ability of people with insomnia.
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Nantong University, Nantong, Jiangsu, China; Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China. Electronic address: lianyulong444@163.com.
authors.forename: Yulong
authors.initials: Y
authors.lastname: Lian
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Nantong University, Nantong, Jiangsu, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ning
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Suzhen
authors.initials: S
authors.lastname: Guan
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Ge
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Fuye
authors.initials: F
authors.lastname: Li
authors.affiliation: Division of Occupational and Environmental Health, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang, China.
authors.forename: Jiwen
authors.initials: J
authors.lastname: Liu
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004526:Efficiency; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012044:Regression Analysis; D012307:Risk Factors; D012890:Sleep; D007319:Sleep Initiation and Maintenance Disorders; D011795:Surveys and Questionnaires; D013997:Time Factors; D014937:Work
keywords: Insomnia; Insomnia symptoms; Sleep duration; Work ability