title: Neuroendocrine recovery after 2-week 12-h day and night shifts: an 11-day follow-up.
abstract: OBJECTIVE
  The study aimed to investigate the course and duration of neuroendocrine recovery after 2-week 12-h day and night shift working periods and to study whether there were differences in recovery between the shift groups.
  
  
  METHODS
  Twenty-nine male offshore employees working 2-week 12-h shift tours participated in the study; 15 participated after a day shift tour and 14 after a night shift tour. Salivary cortisol was assessed at awakening, 30 min after awakening, and before bedtime on the 1st, 4th, 7th, and 11th day of the free period, with a reference day prior to the offshore tour. Differences were tested using generalised estimating equations analysis.
  
  
  RESULTS
  Compared to the reference day, night shift workers had a significantly flatter cortisol profile on the 1st day off, significantly lower cortisol concentrations at 30 min after awakening on day 4 and at awakening on day 7, and a significantly smaller decline to evening concentration on days 4 and 11. Compared to the reference day, day shift workers only showed a significantly lower cortisol concentration at awakening on the 1st day off. Compared to day workers, night shift workers had a flatter profile on the 1st day off and a lower cortisol concentration at awakening on the 4th day.
  
  
  CONCLUSIONS
  Following 2-week 12-h night shift working periods, recovery was not fully complete up to day 11. Following 2-week 12-h day shift working periods, an indication of incomplete recovery was found on the 1st day off, with full recovery reached on day 4.
authors: Research Group Work and Safety, International Research Institute of Stavanger, P. O. Box 8046, 4068, Stavanger, Norway.
authors: Suzanne L
authors: SL
authors: Merkus
authors: Kari Anne
authors: KA
authors: Holte
authors: Maaike A
authors: MA
authors: Huysmans
authors: Åse Marie
authors: ÅM
authors: Hansen
authors: Peter M
authors: PM
authors: van de Ven
authors: Willem
authors: W
authors: van Mechelen
authors: Allard J
authors: AJ
authors: van der Beek
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology*; D019652:Extraction and Processing Industry; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009490:Neurosecretory Systems / Q000502:physiology*; D009664:Norway; D009792:Oceans and Seas; D061329:Oil and Gas Fields; D012463:Saliva; D011795:Surveys and Questionnaires; D013997:Time Factors; D014940:Work Schedule Tolerance / Q000502:physiology*
chemical_list: D006854:Hydrocortisone