Effort-reward imbalance, sleep disturbances and fatigue.

Objectives: The objective of this study was to investigate the validity of the effort–reward imbalance (ERI) model in relation to disturbed sleep and fatigue. Methods: The study population derived from a subset of the WOLF (WOrk, Lipids, Fibrinogen) cohort study of cardiovascular risk in a working population who replied to the ERI-questionnaire comprising 789 men and 214 women. Cox regression analysis was used to calculate the prevalence ratio (PR) for sleep disorders and fatigue in relation to the components of ERI. Results: As sleep disturbances and fatigue, based on literature, were defined to be represented by the uppermost quintile, 14% of the men and 23% of the women were affected by sleep disturbances while 14 and 26%, respectively, were affected by fatigue. Higher levels of exposure for the ERI components were associated with increased prevalence of sleep disturbances and fatigue. For men, the strongest association was seen between high overcommitment and fatigue (PR 5.77, 95% confidence interval 2.89–11.5). For women, high effort and sleep disturbances (PR 4.04, CI 1.53–10.7), high effort/reward ratio and sleep disturbances (PR 4.13, CI 1.62–10.5), and between low reward and fatigue (PR 4.36, CI 1.79–10.6) yielded the most obvious associations. Conclusions: The present study adds sleep disturbances and fatigue to the list of adverse consequences of effort–reward imbalance.