This book is the result of three years of work by a team of authors. The study was conducted at the Department of Hospital Therapy No.1, Faculty of Medicine, Pirogov Russian State Medical University. The study was conducted at the Department of Hospital Therapy No.1, Faculty of Medicine, Pirogov Russian State Medical University, under the supervision of Prof. V.A. Lyusov. Materials on the problem of night sleep apnea syndrome are presented. The relationship between disorders of breathing during sleep and pathology of the cardiovascular system is discussed in detail. Particular attention is paid to the influence of night sleep apnea syndrome on the clinical course of coronary heart disease: angina pectoris IV F.K. The results of his own research with the assessment of data of daily ECG monitoring, lipid profile, C-reactive protein, as well as the influence of the severity of night sleep apnea syndrome on the prognosis of the main disease are presented.