Are changes in workplace bullying status related to changes in salivary cortisol? A longitudinal study among Danish employees.

Objectives: This study aims to investigate whether incident workplace bullying and its dicontinuance is related to subsequent change in morning and evening saliva cortisol concentrations.

Methods: Participants came from two Danish cohort studies, the PRISME cohort (n=4489) and the Workplace Bullying and Harassment Cohort (n=3707). At baseline and follow-up exposure to bullying was measured by a single question on bullying (preceded by a definition). Two saliva samples to measure cortisol were collected during a work-day (30 min after awakening and at 8 p.m.). All participants responding to the item on workplace bullying, giving saliva samples and participated at both baseline and follow-up were included. The reference group consisted of non-bullied respondents at both baseline and follow-up. Multilevel mixed-effects linear regressions were used to test for changes in salivary cortisol after newly onset of and discontinuance of workplace bullying. All analyses were adjusted for the potentially confounding effect of differences from baseline to follow-up in education, smoking, alcohol consumption, body mass index, cohort, sampling waves, time of awakening, and time of sampling.

Results: We found no indication of statistically significant difference in saliva cortisol, neither when participants changed their self-labelling from not bullied at baseline to being bullied at follow-up, nor when they at follow-up two years later reported discontinuance of bullying.

Conclusion: This longitudinal study on the impact of changes in bullying status on change in cortisol levels showed consistent lack of associations with onset and discontinuance of workplace bullying.