PURPOSE: The aims of the present study were to investigate whether being subjected to bullying and witnessing bullying at the workplace was associated with concurrent sleep difficulties, whether frequently bullied/witnesses have more sleep difficulties than occasionally bullied/witnesses, and whether there were associations between being subjected to bullying or witnessing bullying at the workplace and subsequent sleep difficulties. METHODS: A total of 3,382 respondents (67 % women and 33 % men) completed a baseline questionnaire about their psychosocial work environment and health. The overall response rate was 46 %. At follow-up 2 years later, 1671 of those responded to a second questionnaire (49 % of the 3,382 respondents at baseline). Sleep difficulties were measured in terms of disturbed sleep, awakening problems, and poor quality of sleep. RESULTS: Bullied persons and witnesses reported more sleep difficulties than those who were neither bullied nor witnesses to bullying at baseline. Frequently bullied/witnesses reported more sleep difficulties than respondents who were occasionally bullied or witnessing bullying at baseline. Further, odds ratios for subsequent sleep difficulties were increased among the occasionally bullied, but not among witnesses. However, the associations weakened when adjusting for sleep difficulties at baseline. CONCLUSION: Being subjected to occasional bullying at baseline was predictive of subsequent sleep difficulties. Witnessing bullying at baseline did not predict sleep difficulties at follow-up.