Objective: The cortisol increase after awakening has been shown to be associated with work-related stress. Several studies demonstrated a moderate stability of cortisol awakening responses on subsequent days, suggesting situation-dependent variance. This study tests whether cortisol awakening responses are different on weekdays compared with weekend days and whether such differences may be explained by chronic work overload and worrying.
Methods: Two hundred nineteen participants took saliva samples immediately after awakening and 30, 45, and 60 minutes later on 6 consecutive days starting on Saturday. Perceived chronic work overload and worrying were assessed by a standardized questionnaire.
Results: There is a clear weekend-weekday difference in the cortisol response to awakening. This difference is associated with chronic work overload and worry. Independent of sex and weekend-weekday differences in time of awakening and sleep duration, participants who report higher levels of chronic work overload and worrying show a stronger increase and higher mean levels of cortisol after awakening on weekdays, but not on weekend days.
Conclusions: The weekend-weekday differences in the cortisol awakening response and their association with chronic stress clearly demonstrate that the day of cortisol assessment is crucial in psychoendocrinological stress studies.