Work hours and cortisol variation from non-working to working days.
OBJECTIVE
This study aims at modelling the relationship between the number of work hours per week and cortisol variation across 3 days by comparing non-working day to working day in a population of day-shift workers.


METHODS
Questionnaire data and saliva samples for cortisol analysis were collected on 132 day-shift workers employed in 13 workplaces in Canada. Consenting workers provided 5 saliva samples a day (awaking, 30 min after awaking, 2 p.m., 4 p.m., bedtime) repeated 3 times (Saturday, Tuesday, Thursday) over a week, to provide measures at work and non-work times and settings. Multilevel regression models were estimated from cortisol measurements at each occasion within a day at level-1, days at level-2 and workers at level-3.


RESULTS
Controlling for gender and age, results revealed significant variations in salivary cortisol concentration between sample, day and worker levels. Cortisol increases linearly from non-working day to work days and work hours per week interacted with days, revealing a positive association between the number of work hours per week and cortisol concentrations during these days. Work hours per week did not interact with awaking, 30 min after awaking, 2 p.m., 4 p.m., and bedtime cortisol concentrations. Gender and age had neither main effects nor interaction effects. No significant cortisol variations were found between workplaces.


CONCLUSIONS
These results suggest that work hours act as a stressor that is associated with significant variations in cortisol concentrations over working days. Non-working days may contribute to stress reduction in workers who experience longer work hours.
School of Industrial Relations, University of Montreal, C.P. 6128, Succ Centre-ville, Montreal, QC, H3C 3J7, Canada. alain.marchand@umontreal.ca
Alain
A
Marchand
Pierre
P
Durand
Sonia
S
Lupien
D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D012044:Regression Analysis; D012463:Saliva / Q000378:metabolism*; D013312:Stress, Physiological / Q000502:physiology*; D013315:Stress, Psychological / Q000378:metabolism*; D011795:Surveys and Questionnaires; D013997:Time Factors; D014940:Work Schedule Tolerance / Q000502:physiology* / Q000523:psychology; D016526:Workload / Q000523:psychology
D015415:Biomarkers; D006854:Hydrocortisone