Purpose: To investigate the association between two job stress models-the job demand-control model and the effort-reward imbalance model-and repeated measures of salivary cortisol among male and female call-centre operators.
Methods: Daily cortisol profiles consisting of seven time points were measured across two workdays and one leisure day to determine the cortisol awakening response and the cortisol output in the day in 104 volunteers. The employees completed two self-administered questionnaire--the Karasek's demand-control questionnaire and the Siegrist's effort-reward imbalance questionnaire-to assess psychosocial hazards at work. The relations between the perceived workload measures and salivary cortisol levels were analyzed by means of generalized estimating equations method after adjusting for potential confounders (gender, age, educational level, marital status, morning awakening time, sleep duration and quality, weekdays, work schedule, adherence to sampling procedure).
Results: The total cortisol amount excreted in the awakening period was positively associated with the job strain measures (high strain vs. low strain: 1.4 (2.4-0.3) nmol/l). In contrast, individuals scoring higher in effort-reward imbalance at work had both lower cortisol awakening response (high imbalance vs. low imbalance: -0.7 (-1.3 to -0.2) nmol/l) and lower diurnal secretory activity (-9.2 (-17.7 to -0.7) nmol/l). Gender, weekday and adherence to sampling schedule significantly influenced the cortisol excretion in the morning period.
Conclusions: Our results indicate that the two work stress models differentially affect salivary cortisol output. This finding suggests that combining the information from two complementary job stress models results in improved knowledge on the psychobiological correlates of the psychosocial work environment.