Sleep apnea syndrome, or snoring, is clinically divided into the following categories: 1. Obstructive sleep apnea syndrome This is the most common type of sleep apnea syndrome. The patient’s upper airway is obstructed during sleep, probably due to excessive throat tissue or relaxation of the muscles that keep the airway open. The air cannot pass through the airways smoothly, resulting in apnea. This type of patient is usually characterized by heavy snoring, and middle-aged men are the most common. The specific causes of obstructive disease are: (1) nasal lesions (2) oral lesions (3) pharyngeal lesions (4) systemic diseases (2) central sleep apnea syndrome. Central type is seen in the respiratory center damage and some cranio-cerebral diseases. 3, Mixed sleep apnea syndrome Patients suffer from both obstructive and central sleep apnea syndrome.