Sleep disturbances constitute one of the important yet underestimated aspects of functioning of patients with multiple sclerosis (MS). The objective of this study was to evaluate sleep disturbances in patients with MS, with regard to demographic factors, disease-related variables, co-existing conditions and fatigue. In 100 MS patients, Epworth Sleepiness Scale (ESS) and a questionnaire about sleep disturbances (SlD) were implemented. ESS and SlD results were analyzed with regard to age, gender, duration of MS, type of its course, degree of disability in Expanded Disability Status Scale (EDSS), MS therapies, coexisting diseases, results of Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS). ESS score indicated increased daytime sleepiness in 19 patients. In SlD, 49 subjects reported sleep disturbances and 35 more than one of their kind (most commonly terminal and middle insomnia). No relationships were found between ESS and SlD scores and age, gender, MS duration, type of its course, EDSS or coexisting diseases. In 36 patients, somatic complaints interfered with sleep. The patients with depression had significantly lower ESS result and those currently treated with immunomodulation had significantly lower SlD score. SlD score correlated positively with FSS and MFIS. Sleep disturbances in MS patients may occur independently from demographic and disease-related variables, but they are often influenced by the symptoms of MS and therapies used. Sleep disturbances may contribute to fatigue in the course of MS.