Insomnia is Associated with the Effect of Inpatient Multimodal Occupational Rehabilitation on Work Participation in Workers with Musculoskeletal or Mental Health Disorders: Secondary Analyses of a Randomized Clinical Trial

STUDY OBJECTIVES: Insomnia is common among people with musculoskeletal and/or mental health disorders. This study aimed to assess whether insomnia is associated with the favorable effect from inpatient multimodal occupational rehabilitation on future work participation among individuals with these conditions. METHODS: Insomnia was measured at baseline through a randomized clinical trial that compared the effect of inpatient multimodal occupational rehabilitation with a less-comprehensive program of outpatient acceptance and commitment therapy on future work participation. The inpatient multimodal program lasted 3.5 weeks at the rehabilitation center, comprising psychoeducational sessions (including sleep education), fixed schedules, acceptance and commitment therapy, physical exercise and work-related problem-solving, whereas the outpatient program comprised mainly six weekly acceptance and commitment therapy sessions. Both programs were group-based. The study tracked cumulative sick leave during the 12 months of follow-up using national registry data. RESULTS: Among the 163 adults included in this subgroup analysis, 56% (n=91) reported insomnia. Overall, we found statistical evidence of interaction between the occupational program and insomnia concerning cumulative sick leave (p=0.03). Compared with people without insomnia in the comprehensive inpatient multimodal program, people with insomnia had 12 (95% CI: −48 to 24) fewer days with sick leave if they participated in the inpatient program and 46 (95% CI: 8 to 83) more days if they participated in the outpatient program. CONCLUSION: These findings suggest that insomnia should be addressed specifically before individuals on sick leave are considered for participation in occupational rehabilitation and that individuals with insomnia may benefit in particular from inpatient rehabilitation.