Subjective Sleep Quality in Relation to Relapse Status in Relapsing-Remitting Multiple Sclerosis: A Propensity Score‒Matched Nested Case‒Control Analysis

Background: Sleep disturbance is common in multiple sclerosis (MS), but its relationship with relapse status remains insufficiently defined. This study examined whether poorer subjective sleep quality was associated with relapse status in patients with relapsing-remitting multiple sclerosis. Methods: This propensity score–matched nested case–control analysis included 132 patients with relapsing-remitting MS selected from 473 consecutively evaluated patients at a tertiary multiple sclerosis centre. Patients in relapse were matched 1:1 to patients in remission by age, sex, disease duration, Expanded Disability Status Scale score, disease-modifying therapy duration and efficacy class, and relapse in the previous year. Sleep quality and related symptoms were assessed using validated questionnaires. Results: Patients in relapse were more frequently classified as poor sleepers than those in remission (59.1% vs. 36.4%; p = 0.009). In the double-adjusted logistic regression model, higher Pittsburgh Sleep Quality Index scores were independently associated with relapse status (OR = 1.16; 95% CI 1.02–1.32; p = 0.023), whereas the remaining variables were not independently associated with relapse status. Conclusions: Poorer subjective sleep quality was independently associated with relapse status in relapsing-remitting MS, supporting sleep disturbance as a relapse-associated clinical feature rather than a proven causal risk factor.