title: Effects of fatigue on immune function in nurses performing shift work.
abstract: OBJECTIVE
  We investigated the effects of fatigue on NK cell function and lymphocyte subpopulations in nurses performing shift work using a longitudinal design.
  
  
  METHODS
  Fifty-seven female nurses engaged in shift work at a hospital in Japan were selected for our study cohort. The hospital used a counterclockwise rotating three-shift system. Night shifts followed day shifts after a seven-hour interval. Immune parameters measured at the beginning of the day shift through to the end of the night shift were compared between two groups stratified by their level of fatigue. Statistical differences were evaluated after adjusting for baseline immune values and other demographic features.
  
  
  RESULTS
  Subjective feelings of fatigue increased progressively from the beginning of day shifts to the end of night shifts. From the beginning of day shifts to the end of night shifts, NK cell activity and CD16(+)CD56(+) lymphocytes decreased, while CD3(+) and CD4(+) lymphocytes increased. The group with the greater increase in fatigue showed a larger decrease in NK cell activity and a larger increase in CD4(+)lymphocytes when compared with the group reporting less fatigue. These findings did not change after adjusting for demographic factors and sleep hours.
  
  
  CONCLUSIONS
  Our data suggest that shift work has deleterious effects on NK cell function and that the effects depend on the degree of fatigue. Proper management of shift work may lessen fatigue in workers and also ameliorate many health problems experienced by shift workers.
authors.affiliation: Department of Epidemiology and Public Health, Kanazawa Medical University, Japan. m-long@kanazawa-med.ac.jp
authors.forename: Makie
authors.initials: M
authors.lastname: Nagai
authors.forename: Yuko
authors.initials: Y
authors.lastname: Morikawa
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Kitaoka
authors.forename: Koshi
authors.initials: K
authors.lastname: Nakamura
authors.forename: Masaru
authors.initials: M
authors.lastname: Sakurai
authors.forename: Muneko
authors.initials: M
authors.lastname: Nishijo
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hamazaki
authors.forename: Shoko
authors.initials: S
authors.lastname: Maruzeni
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nakagawa
mesh_terms: D000328:Adult; D017252:CD3 Complex; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D019002:CD56 Antigen; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005221:Fatigue / Q000276:immunology*; D005260:Female; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008137:Longitudinal Studies; D008875:Middle Aged; D009741:Nursing Staff, Hospital; D017452:Receptors, IgG; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014940:Work Schedule Tolerance / Q000502:physiology*; D055815:Young Adult
chemical_list: D017252:CD3 Complex; D019002:CD56 Antigen; D017452:Receptors, IgG