title: [Fatigue and workability in twelve-hour fixed shifts].
abstract: OBJECTIVE
  To analyze the variables associated with fatigue perception and workability on workers working 12-hour fixed night and day shifts.
  
  
  METHODS
  A cross-sectional study was carried out. Forty-three workers, working 12-hour fixednight and day shifts in a textile factory, filled out questionnaires about fatigue, workability index, individual characteristics, life style and working conditions. A univariate linear regression analysis was performed.
  
  
  RESULTS
  Fatigue-related factors are associated to the workers' life style (physical activities is a protection factor), and sleep difficulties, with may increase fatigue perception. Workability-related factors are associated to longevity on job and working night shifts - workability index decreases as job longevity increases. Working night shifts showed a higher workability index. The 12-hour shifts may cause a considerably higher workload, influencing worker's perception of fatigue and workability index and sleep disturbances.
  
  
  CONCLUSIONS
  The results indicate that night shifts may not always be translated a health problem. However, this was a cross-sectional study with a small population sample and selection bias is not excluded. Since the workability index reduces while job longevity increases, there is a need for further longitudinal studies with larger population samples.
authors.affiliation: Departamento de Saúde Ambiental, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: R J
authors.initials: RJ
authors.lastname: Metzner
authors.forename: F M
authors.initials: FM
authors.lastname: Fischer
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005221:Fatigue; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D010561:Personnel Staffing and Scheduling; D012044:Regression Analysis; D011795:Surveys and Questionnaires; D013997:Time Factors; D014940:Work Schedule Tolerance