title: Survey and comparison of sleep quality among fixed and changing shift staff in a steel factory in Tehran, Iran.
abstract: BACKGROUND
  Given the hazardous nature of the work in steel factories and that the staff has to deal with hazardous equipment and machines, improper sleep quality and drowsiness among the works tackles performance and boosts rate of job accidents. This study is aimed to survey the quality of sleep and sleepiness status and the pertinent factors among the workers in a rolling mill and a steel production company in Tehran, Iran.
  
  
  METHODS
  In a Cross-Sectional study 2011, 180 workers were selected randomly from a rolling mill and a steel production company in Tehran. A questionnaire was designed to collect demographic data and variables of work condition. Pitersborg's sleep quality questionnaire was used to survey quality and problems of Participants' sleep. Epworth Sleepiness questionnaire was used to deals with sleepiness during work, studying, watching TV, or during time spent in public.
  
  
  RESULTS
  Average score of sleep quality for the fixed shift staff and changing shift staff were 7.5±2.82 and 8.49±2.95 respectively. Surveys of sleep quality for the two groups of the participants based on T-test showed a significant difference between the two groups so that the changing shift staff group suffered poorer sleep quality (p=0.03). Comparison of average drowsiness scores between the two groups of participants based on Mann-Whitney test showed no significant difference (p>0.005). Chi square test showed a significant difference between severity of drowsiness and type of working shift (p =0.028 and 0.009).
  
  
  CONCLUSIONS
  Staff in revolving shifts suffers poor sleep quality comparing with staff with fixed working shift. Moreover, type of working shift greatly affects severity of drowsiness as staff at different work shift experienced different level of sleepiness. It is essential to survey sleep disorder of the staff in the industry and pay more emphasis on sleep disorder epidemic in other fields of industry.
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Farugh
authors.initials: F
authors.lastname: Mohammadian
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Abbasinia
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Abdolrasoul
authors.initials: A
authors.lastname: Rahmani
authors.affiliation: Associate Professor of Occupational Health, Department of Occupational health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Monazzam
authors.affiliation: Ph.D. Student of Occupational Health, Department of Occupational Health, Arak University of Medical Sciences, Arak, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Asghari
authors.affiliation: MD of Industrial Medicine of Oil Company, Iranian petroleum industry health research institute, Tehran, Iran.
authors.forename: Iman
authors.initials: I
authors.lastname: Ahmadnezhad
authors.affiliation: M.Sc. of chemistry, Hmadan, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Asadi
keywords: Fixed shift staff; Occupational health; Sleep quality; Sleepiness; Steel production