Objective. To study the characteristics of nocturnal sleep and reveal breathing disorders during sleep in ALS patients using polysomnography. Material and methods. The study included 29 patients with the established diagnosis of ALS, 17 women and 12 men, median age 65 [59; 68] years; mean illness duration 12 [22.9; 27.1] months. The control group consisted of 46 volunteers without complaints of sleep disorder and sleep apnea. The sleep diagnostic system Somnolab 2 Weinmann, Germany was used. Results and conclusion. An increased level of awaketime and a significant decrease in amount of deep sleep and REM sleep were revealed in ALS patients. Sleep breathing disorders are found significantly more often in ALS patients, mainly as alveolar hypoventilation syndrome and less frequently as obstructive sleep apnea. The lower level of mean and minimum blood oxygen saturation and increased respiratory rate were detected. These changes are possibly due to the presence of restrictive respiratory disorders. These disturbances reduce the total duration of sleep, destroy it’s structure, exerting a direct influence on the life quality in ALS patients, disrupting their domestic and social activity, contributing to the development of neuropsychological and behavioral disorders.