BackgroundObstructive sleep apnea (OSA) is more common in patients with multiple sclerosis (MS) than in the general population, which suggests MS may predispose patients to OSA. However, the relationships between MS treatment, disease activity, disease severity, fatigue, and OSA are unknown. ObjectivesTo evaluate the connections between OSA risk, MS fatigue, and MS severity, controlling for well-established risk factors for OSA in the general population. MethodsWe administered OSA and fatigue-related questionnaires to patients with MS and collected relevant demographic and clinical data. Then, we utilized multivariate logistic regression to examine relationships between OSA risk and MS disease severity. ResultsWe identified an inverse correlation between medication possession ratio (MPR) and high OSA risk. Statistical models also demonstrated a positive correlation between fatigue and nonwhite race with high OSA risk, controlling for male sex, younger age, and body mass index (BMI). ConclusionWe identified disease-modifying therapy (DMT) underutilization, fatigue, and nonwhite race as predictors of high OSA risk in patients with MS. These findings support aggressive treatment of MS to avoid risk of comorbid OSA and MS-induced fatigue.