Objectives. To study the clinical and neurophysiological features of sleep disturbances in patients with different forms of multiple sclerosis (MS) and their effects on quality of life and the course and prognosis of illness; to identify the influences of sleep disturbances on the formation and maintenance of chronic fatigue syndrome in MS patients. Materials and methods. A total of 54 patients with different forms of MS and 54 healthy volunteers were studied. General clinical investigation methods were used, along with neuropsychological testing (detection of anxious-depressive states), subjective sleep quality assessment scales (assessment of the severity of daytime drowsiness, chronic fatigue syndrome, quality of life measures), and their subsequent relationship with neuroimaging and neurophysiological data. Results and discussion. Analysis of the data revealed a high frequency of sleep disturbances associated with anxiety disorders and other comorbid pathologies which occur significantly more frequently among MS patients.