OBJECTIVES: This study aimed to analyze if adverse psychosocial working conditions, defined by the model of effort-reward imbalance (ERI), increase the risk of sleep disturbances in the Danish workforce. METHODS: Analyses were conducted both cross-sectionally and prospectively in a representative sample of Danish employees. The cross-sectional sample included 2614 participants (50% women) aged 18-59 years, of whom 263 had sleep disturbances. Of the 2351 participants initially free of sleep disturbances, 304 (12.9%) developed sleep disturbances during the 5-year follow-up. Data were analyzed with gender-stratified, multivariate logistic and linear regression analyses, adjusted for numerous covariates. RESULTS: Cross-sectionally, a 1 S.D. increase in the ERI ratio was associated with sleep disturbances among both men [odds ratio (OR)=1.65, 95% confidence interval (CI)=1.20-2.27] and women (OR=1.82, 95% CI=1.46-2.28). In the prospective analysis, a 1 S.D. increase of the ERI ratio at baseline predicted the onset of sleep disturbances among men (OR=1.39, 95% CI=1.03-1.87) but not among women (OR=0.97, 95% CI=0.76-1.24). CONCLUSION: Among men, ERI is a risk factor for the development of sleep disturbances in the Danish workforce. Among women, an association between ERI and sleep disturbances was restricted to the cross-sectional sample. Improving psychosocial working conditions might reduce the risk of sleep disturbances and subsequently also help to prevent clinical disorders related to sleep disturbances.