Obstructive sleep apnea syndrome, abbreviated as OSAS, is a more complex disease caused by some causes of upper airway obstruction, with apnea during sleep, accompanied by hypoxia, snoring, daytime sleepiness and other symptoms. It is more common in obese and elderly people. OSAS can be caused by obstructive lesions in any part of the upper respiratory tract. Symptoms and signs It is common in 40-60 years old and more common in overweight middle-aged and elderly men. The clinical features consist of loud snoring, brief shortness of breath and alternating apnea lasting more than 10 seconds. The apnea may produce a sense of suffocation and may be accompanied by body movements that may cause sudden awakening, followed by several breaths before falling asleep again. Frequent turning or limb movement during sleep can kick and injure bedmates; sometimes suddenly sitting up, mouthing the words, and suddenly falling asleep again. During the day, you may feel fatigue, sleepiness, lack of energy, morning headache, sluggishness, as well as decreased memory, attention, judgment and alertness. Depression, anxiety, irritability, dry mouth, loss of libido and hypertension may occur. Disease etiology Abnormalities in the nasopharyngeal structures leading to narrowing of the upper airway are the main cause of airway obstruction during sleep. Diagnostic tests Polysomnography is the gold standard for the diagnosis of this disease. During 7 hours of sleep per night, there are more than 30 repeated episodes of apnea for more than 10 seconds each, or apnea hypoventilation index (AHI; refers to the total number of apnea and hypoventilation per hour averaged over the whole night sleep period) > 5 times. Hypoventilation is defined as a reduction in respiratory airflow of 50% or more for more than 10 seconds. Apnea is common in NREM sleep stages 1 and 2, rare in stages 3 and 4, and most common in REM sleep. NREM sleep stages 3 and 4 are shortened, and the average sleep latency is often less than 10 minutes. Treatment options Non-surgical treatments are available, such as weight loss, lateral sleep, avoidance of alcohol before bedtime, and sedation. An effective therapy commonly used today is continuous positive airway ventilation via the nose, where a mask connected to a ventilator is worn during sleep and the forced airflow generated by the ventilator increases the pressure in the upper airway, maintaining a constant pressure regardless of the inspiratory or expiratory state, so that the upper airway is always open and avoids collapse or obstruction. Different types of oral appliances can also be used during sleep to lift the mandible or tongue forward and upward to increase the cross-sectional area of the pharynx and increase respiratory airflow. Surgical treatment, such as uvulopalatopharyngoplasty, is possible when necessary.