Sleep and fatigue in multiple sclerosis: A questionnaire-based, cross-sectional, cohort study

Introduction Fatigue and sleep disorders are frequently reported in patients affected by Multiple Sclerosis (MS) but the causes and the relationship are not yet fully understood. This study aimed at evaluating their prevalence, at determining the relationships between clinical findings of MS and the occurrence of sleep disorders and at investigating the relations between sleep disorders and fatigue. Methods One hundred and two MS patients were enrolled in the study. They were analyzed on both their clinical features (type of MS, disease duration, clinical severity, type of treatment, presence of spinal demyelinating lesions) and specific scales scores (Expanded Disability Status Scale, Modified Fatigue Impact Scale - MFIS, Self-Administered Anxiety Scale - SAS, Beck's Depression Inventory - BDI, Pittsburgh Sleep Quality Index - PSQI, Epworth Sleepiness Scale - ESS, and the Berlin's questionnaire for Obstruction Sleep Apnea Syndrome - OSAS). Results Patients with poor sleep quality are more frequently fatigued (p = 0.001), have higher MFIS global scores (p < 0.001), higher prevalence of RLS symptoms (p = 0.049), and show higher scores at BDI (p = 0.017) and SAS (p ≤ 0.001). Conversely patients with fatigue show older age (p = 0.005), higher prevalence of sleepiness (p = 0.021), higher prevalence of RLS symptoms (p = 0.030), higher prevalence of poor sleep quality (p < 0.001) with higher PSQI scores (p < 0.001), higher scores on the BDI (p < 0.001) and SAS (p ≤ 0.001). Conclusion This study shows that MS is associated with a high prevalence of sleep complaints, including subjectively poor sleep quality, excessive daytime sleepiness, RLS and symptoms of OSAS. Further, it demonstrated a strict relation between fatigue and sleep disorders. Finally, it underlines their relationship with anxiety and depression in MS patients.