title: Heavy overtime work and depressive disorder among male workers.
abstract: BACKGROUND
  The association between overtime and depression is unclear and very few studies have examined the association between heavy overtime work, i.e. working more than 60 h per week, and depression.
  
  
  OBJECTIVE
  To examine the association between heavy overtime work and the onset of depressive disorder among male workers.
  
  
  METHODS
  A 1-year follow-up cohort study of male workers in a manufacturing company in Japan, between 2008 and 2009. Working hours, depressive disorder, assessed by the Center for Epidemiologic Studies Depression (CES-D) Scale (score ≥16 points), and covariates were measured at baseline and at follow-up. Participants who had depressive disorder at baseline were excluded.
  
  
  RESULTS
  At follow-up, 1194 participants aged between 18 and 71 years were analysed. Multiple logistic regression analysis revealed that the odds ratio for the new onset of depressive disorder was 4.5 (95% CI 1.8-11.1) times higher for employees working >60 h per week than for those working ≤50 h per week, when adjusted for age, lifestyle factors, work-related characteristics and socio-demographic characteristics at baseline and working hours at follow-up. However, the correlation between working 50.1 to 60 h per week and depressive disorder was not significant. The trend test of depressive disorder among groups by working hours was significant (P < 0.01).
  
  
  CONCLUSIONS
  Heavy overtime work is a risk factor for the new onset of depressive disorder in this population of male workers. Working >60 h per week may be the cut-off to screen for high-risk groups who need preventive action against depressive disorder.
authors.affiliation: Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan, rimka@mail.goo.ne.jp.
authors.forename: R
authors.initials: R
authors.lastname: Kato
authors.affiliation: Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Haruyama
authors.affiliation: Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Endo
authors.affiliation: Department of Public Health, Kitasato University School of Medicine, Kanagawa 252-0374, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tsutsumi
authors.affiliation: Department of Public Health, Dokkyo Medical University School of Medicine, Tochigi 321-0293, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Muto
mesh_terms: D000328:Adult; D000368:Aged; D003863:Depression / Q000453:epidemiology / Q000523:psychology*; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000523:psychology*; D016017:Odds Ratio; D013997:Time Factors; D014940:Work Schedule Tolerance / Q000523:psychology*; D016526:Workload / Q000523:psychology* / Q000706:statistics & numerical data
keywords: CES-D; depressive disorder; overtime work; working hours.