workplace bullying

Researchers study the effects of workplace bullying on sickness absence and whether the relationship can be explained by its effect on cortisol levels.

Long-term sickness absence comes at a cost, not only to the individual but also to society.  Psychosocial work factors are among the many factors that can lead to long-term sickness absence.  One of those factors is workplace bullying, although the mechanisms by which workplace bullying contributes to long-term absence is unknown.

Activation of the hypothalamus-pituitary-adrenal axis (HPA-axis) and its subsequent changes in cortisol secretion is a possible biological pathway linking psychological stress to somatic diseases.  Cortisol is a hormone that regulates a wide range of processes throughout the body, including metabolism, immune response, and stress.  Somatic diseases are physical symptoms that are experienced by the body due to psychological factors such as headaches, nausea or vomiting, dizziness, and fainting.

Cortisol levels vary greatly from person to person and also throughout the day.  Usually, cortisol levels are high in the morning and then fall throughout the day.  The results of previous research are inconsistent – but some research indicates that low levels of cortisol in the morning and high levels in the evening are related to poor somatic health – but not poor mental health.  Studies have shown that people who are bullied tend to have lower daytime circulating cortisol concentrations.  Studies of this nature typically assess cortisol levels through saliva sampling.

Studies have shown that acute stress increases HPA-axis activity, but chronic stress lowers HPA-axis activity.  This led Danish researchers to hypothesize that early stages of workplace bullying will lead to higher cortisol levels, proceeded by a shift towards lower cortisol levels as the bullying becomes prolonged.  There has been a dearth of research investigating whether cortisol levels are predictors of future long-term workplace absences.  Additionally, there have been no studies thus far examining if workplace bullying and long-term sickness is mediated by cortisol levels.

This study examined to what extent morning or evening cortisol levels were associated with long-term sickness absence and if cortisol mediated the association between workplace bullying and long-term absence. The scientists hypothesized that participants with lower morning and evening cortisol levels would exhibit a higher occurrence of long-term sickness absence and that the association between long-term sickness absence and bullying would be mediated by cortisol concentrations.

The test this hypothesis, the scientists used data from two well-known Danish cohorts, the “Psychosocial Risk factors for Stress and Mental disease” (PRISME)  and the “People and Workplace Bullying and Harassment” cohort (WBH).  The study included 5418 unique participants in total and included 7,451 observations.  The final analysis included saliva samples from 161 participants who experienced workplace bullying and 148 participants as controls.

The results, recently published in BMC Public Health, were surprising.  Contrary to the hypothesis, the researchers found no indication that cortisol mediated the association between workplace bullying and long-term sickness absence.  There was no support for the hypothesis that cortisol is part of the causal pathway leading from workplace bullying to long-term sickness leave.  The researchers did, however, find that evening cortisol levels are associated with a decreased risk of sickness absence.  They also found that workplace bullying was significantly associated with long-term sickness absence and interestingly that the reverse was also true; long-term sickness absence was significantly associated with future bullying.  There was no overall association between bullying and cortisol levels.

Workplace bullying comes at high cost to society and can have serious detrimental effects on the mental health of the survivors.  While we know that workplace bullying is associated and future long-term sickness leave, this study shows that the reverse is also true.  Prevention programs should be mindful of long-term sickness absence as a risk factor for workplace bullying.  This study demonstrated that while workplace bullying can lead to long-term sickness absence, the pathway is not through its effect on cortisol levels, and future research should examine other possible causes.

Written by Lisa Borsellino, B.Sc.

Reference: Grynderup MB, Nabe-Nielsen K, Lange T, et al. The associations between workplace bullying, salivary cortisol, and long-term sickness absence: a longitudinal study. BMC Public Health. 2017 September 16.

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