The most common cause of apnea during sleep is the occurrence of obstructive sleep apnea syndrome. This disorder is a narrowing or blockage of the upper airway that occurs while the patient is sleeping, causing the patient to have impaired ventilation, have significant snoring, have prolonged pauses in breathing, and tend to have sleepiness and excessive sleepiness during the day. Patients with apnea can see the presence of chest and abdominal breathing with heaving, but no airflow at the mouth and nose. The disease is more common in men than in women, and the older the patient, the more likely it is to occur in patients who are obese and have more fat in the neck. Some patients also have nasopharyngeal disorders, such as adenoid enlargement of the tonsils and deviated nasal septum. Sleep apnea may also be caused by long-term heavy alcohol consumption or the use of hypnotic sedatives, endocrinological diseases such as hypothyroidism and acromegaly. Genetic diseases may also have an effect, such as Down syndrome and chondrodysplasia.