title: Offshore fleet workers and the circadian adaptation of core body temperature, blood pressure and heart rate to 12-h shifts: a field study.
abstract: OBJECTIVE
  The aim of this study was to investigate the circadian adaptation of tcr (core body temperature), BP (blood pressure), HR (heart rate) and subjective sleep quality after 7 days of working 12-h night shifts in offshore fleet workers.
  
  
  METHODS
  Night workers (N = 7) (18:00-6:00) and day workers (N = 7) (6:00-18:00) were recruited from a Norwegian offshore company operating in the North Sea. We measured t(cr), BP and HR on days 1 and 7.
  
  
  RESULTS
  An increase of 0.6 °C (p = .03) was observed within the group of night workers from day 1 to day 7. Between the night and day workers there was a significant difference of 0.6 °C from day 1 to day 7 (p = .01). Sleep latency and sleep length also showed significant differences between the groups (p = .01 and p = .04). There was an interaction effect in tiredness during the shift (p = .02).
  
  
  CONCLUSIONS
  The significant increase in tcr indicates an adaptation in the night workers to the new working schedule, and the extended working hours and sleep deprivation are hypothesized to be the main cause of the increased t(cr). Light exposure, altered pattern of food availability and physical activity are likely to have contributed as well. Subjective sleep quality showed inconclusive results.
authors.affiliation: SINTEF Technology and Society, Trondheim, Norway. jakobhonborg.hansen@sintef.no
authors.forename: Jakob Hønborg
authors.initials: JH
authors.lastname: Hansen
authors.forename: Ingunn Holmen
authors.initials: IH
authors.lastname: Geving
authors.forename: Randi Eidsmo
authors.initials: RE
authors.lastname: Reinertsen
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D012890:Sleep / Q000502:physiology*; D018709:Statistics, Nonparametric; D014940:Work Schedule Tolerance / Q000502:physiology*