title: Physical activity, sedentary behavior, and melatonin among rotating shift nurses.
abstract: OBJECTIVE
  To determine the effect of physical activity and sedentary behavior on melatonin levels in a group of rotating shift nurses.
  
  
  METHODS
  Physical activity and sedentary behaviors for 118 nurses were recorded during both a day shift and a night shift using activity diaries, and concentrations of urinary 6-sulfatoxymelatonin were analyzed for each shift.
  
  
  RESULTS
  During the day shift, energy expended in moderate- and vigorous-intensity physical activity between 3 PM and 7 AM was negatively associated with melatonin levels (P = 0.024). During the night shift, energy expended in sedentary behaviors was negatively associated with melatonin levels (P = 0.008).
  
  
  CONCLUSIONS
  Physical activity and energy expended in sedentary behavior are inversely associated with morning urinary melatonin concentrations. Nevertheless, energy expenditure explains a relatively small amount of melatonin variation, perhaps suggesting that peak melatonin is minimally affected by these patterns of physical activity.
authors.affiliation: Department of Community Health and Epidemiology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: McPherson
authors.forename: Ian
authors.initials: I
authors.lastname: Janssen
authors.forename: Anne
authors.initials: A
authors.lastname: Grundy
authors.forename: Joan
authors.initials: J
authors.lastname: Tranmer
authors.forename: Harriet
authors.initials: H
authors.lastname: Richardson
authors.forename: Kristan J
authors.initials: KJ
authors.lastname: Aronson
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology; D001835:Body Weight; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives / Q000378:metabolism / Q000652:urine*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009726:Nurses; D057185:Sedentary Behavior; D012893:Sleep Wake Disorders / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D014940:Work Schedule Tolerance
chemical_list: C054513:6-sulfatoxymelatonin; D008550:Melatonin