OBJECTIVE: This study investigated whether self-reported psychological distress and depressive and burnout symptoms were associated with cortisol concentrations among workers. METHODS: Day-shift workers (N=401) employed in 34 diverse workplaces in Canada participated. We administered well-validated questionnaires and collected salivary cortisol concentrations at five time points (awakening, 30 minutes after awakening, 14:00 hours, 16:00 hours, and bedtime) repeated three times a week (Saturday, Tuesday, Thursday) to capture work and non-workday variation. Multilevel regressions models estimated cortisol concentrations at different levels according to time of day, workers, and workplaces. RESULTS: After controlling for awakening time, sex, age, season of sampling, alcohol use, physical activity, psychotropic drugs use, health conditions, and body mass index, results revealed significant associations between psychological distress and depressive and burnout symptoms in relation to cortisol concentrations at different diurnal time points. Specifically, higher levels of psychological distress and depressive symptoms were associated with higher cortisol concentrations at awakening but not 30 minutes afterwards. Starting steadily from 14:00 hours until bedtime, levels of psychological distress and depressive and burnout symptoms were associated with lower cortisol concentrations. Significant cortisol variations were also found between workplaces. Sex did not moderate associations in secondary analyses. CONCLUSIONS: Distinct time points of diurnal cortisol variation were consistently, albeit modestly, associated with increased psychological distress and depressive and burnout symptoms. Our findings therefore link subjective psychometrics with objective biometrics. This research area could potentially lead to the development of refined screening tools that provide correspondence between diurnal cortisol and mental health.
OBJECTIVE: This study investigated whether self-reported psychological distress and depressive and burnout symptoms were associated with cortisol concentrations among workers. METHODS: Day-shift workers (N=401) employed in 34 diverse workplaces in Canada participated. We administered well-validated questionnaires and collected salivary cortisol concentrations at five time points (awakening, 30 minutes after awakening, 14:00 hours, 16:00 hours, and bedtime) repeated three times a week (Saturday, Tuesday, Thursday) to capture work and non-workday variation. Multilevel regressions models estimated cortisol concentrations at different levels according to time of day, workers, and workplaces. RESULTS: After controlling for awakening time, sex, age, season of sampling, alcohol use, physical activity, psychotropic drugs use, health conditions, and body mass index, results revealed significant associations between psychological distress and depressive and burnout symptoms in relation to cortisol concentrations at different diurnal time points. Specifically, higher levels of psychological distress and depressive symptoms were associated with higher cortisol concentrations at awakening but not 30 minutes afterwards. Starting steadily from 14:00 hours until bedtime, levels of psychological distress and depressive and burnout symptoms were associated with lower cortisol concentrations. Significant cortisol variations were also found between workplaces. Sex did not moderate associations in secondary analyses. CONCLUSIONS: Distinct time points of diurnal cortisol variation were consistently, albeit modestly, associated with increased psychological distress and depressive and burnout symptoms. Our findings therefore link subjective psychometrics with objective biometrics. This research area could potentially lead to the development of refined screening tools that provide correspondence between diurnal cortisol and mental health.