title: A cross-sectional study of the association between working hours and sleep duration among the Japanese working population.
abstract: OBJECTIVE
  This study aimed to clarify the association between long working hours and short sleep duration among Japanese workers.
  
  
  METHODS
  We selected 4,000 households from across Japan by stratified random sampling and conducted an interview survey of a total of 662 participants (372 men; 290 women) in November 2009. Logistic regression analyses were performed using "sleep duration <6 hours per day" as a dependent variable to examine the association between working hours/overtime hours and short sleep duration.
  
  
  RESULTS
  When male participants who worked for ≥7 but <9 hours per day were used as a reference, the odds ratio (OR) for short sleep duration in those who worked for ≥ 11 hours was 8.62 (95% confidence interval [CI]: 3.94-18.86). With regard to overtime hours among men, when participants without overtime were used as a reference, the OR for those whose period of overtime was ≥ 3 hours but <4 hours was 3.59 (95% CI: 1.42-9.08). For both men and women, those with long weekday working hours tended to have a short sleep duration during weekdays and holidays.
  
  
  CONCLUSIONS
  It is essential to avoid working long hours in order to prevent short sleep duration.
authors.affiliation: Department of Public Health, Showa University School of Medicine.
authors.forename: Tadahiro
authors.initials: T
authors.lastname: Ohtsu
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Kaneita
authors.forename: Sayaka
authors.initials: S
authors.lastname: Aritake
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mishima
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Tsuneto
authors.initials: T
authors.lastname: Akashiba
authors.forename: Naohisa
authors.initials: N
authors.lastname: Uchimura
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Nakaji
authors.forename: Takeshi
authors.initials: T
authors.lastname: Munezawa
authors.forename: Akatsuki
authors.initials: A
authors.lastname: Kokaze
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohida
mesh_terms: D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D036301:Qualitative Research; D012890:Sleep; D013997:Time Factors; D014940:Work Schedule Tolerance