The textbook outlines modern views on the etiology, pathogenesis, clinical picture, cardiovascular, metabolic and neurological complications of obstructive sleep apnea syndrome (OSA). The characteristics of the main methods for diagnosing OSA in accordance with the international classification are given. Considerable attention is paid to the choice of optimal treatment tactics depending on the combination of causes and severity of the disease. General preventive, pharmacological, orthodontic and surgical treatment methods are given. The most effective method of treating moderate-severe forms of OSA - non-invasive assisted ventilation with continuous positive pressure during night sleep (CPAP therapy) - is described in detail. The manual is intended for therapists, cardiologists, pulmonologists, neurologists, otolaryngologists, endocrinologists, resuscitators and other doctors interested in the problems of breathing disorders during sleep.