Associations between work stressors, measured by the demand-control-support and effort-reward-imbalance models, and diurnal cortisol concentrations in saliva.

PURPOSE: Chronic exposure to work-related mental stressors has been linked to higher risk of disease, possibly mediated by effects on the normal diurnal cortisol concentration pattern due to allostatic overload. The purpose of this study was to examine if the diurnal cortisol pattern changed with exposure to work-related stressors according to the demand-control-support (DCS) and the effort-reward-imbalance (ERI) stress models. METHODS: In 2007, 4467 Danish public service employees participated in a study on job stress and mental health, and 3217 were reexamined in 2009, using identical methods. DCS and ERI-exposures were assessed from self-administered questionnaires. Cortisol concentrations were assessed from saliva samples, one in the morning and one in the evening. Saliva sampling time distributions enabled us to estimate exposure effects on cortisol concentration patterns for the first two hours after awakening and for nine hours in the evening, and on the peak-to-nadir slope. Associations between the exposures and the diurnal cortisol pattern were examined by linear mixed model analyses, separately for DCS- and ERI-exposures, with mutual adjustment for main and composite variables of the stress model and a large set of potential confounders. RESULTS: DCS- and ERI-exposures were not associated with changes in the diurnal cortisol pattern. In contrast, many associations between potential confounders and cortisol were statistically significant, including the diurnal slope pattern assessed from saliva sampling times. CONCLUSIONS: We found no support for the hypothesis that DCS- or ERI- exposures are associated with changes of the diurnal pattern of cortisol concentrations in saliva samples.