Sleep Disorders and Sleep Disturbances in Persons with Multiple Sclerosis: A Population-Based Matched Case-Control Study in Denmark

Introduction: Adverse sleep is common in multiple sclerosis (MS). Population-based studies including adequate control groups are lacking. We hypothesized that the prevalence of sleep disorders and other sleep disturbances would be higher in persons with MS than in controls. Methods: We conducted a population-based study linking individual-level data from the Danish MS Registry (n = 21,943 persons with MS) and the Danish Population Registry (n = 109,715 matched controls) with information on sleep disorders from the Danish National Patient Registry and other sleep disturbances assessed by dispensed prescription drugs from the Danish National Prescription Registry. Results: Prevalence of diagnosed sleep disorders in terms of central hypersomnia (0.15% vs. 0.06%), sleep disturbances (1.05% vs. 0.70%), and sleep movements (0.22% vs. 0.13%) and other sleep disturbances identified by dispensed central acting (10.73% vs. 1.10%) and hypnotic use (30.65% vs. 20.13%) medication was statistically significantly higher among persons with MS when compared to controls. We found no statistically significant difference in the prevalence of sleep apnea and parasomnia between groups. Stratified by sex and age at MS diagnosis, results for differences between persons with MS and controls were similar. Conclusion: In this registry-based study, we found that the prevalence of several diagnosed sleep disorders was higher in persons with MS than in controls, that is, those reflecting insomnia and daytime symptoms including hypersomnia. Other sleep disturbances identified by dispensed prescription medication were markedly higher in persons with MS than in controls.