The most obvious symptom of sleep apnea is severe snoring, followed by a short pause and then snorting or gasping for breath. Cessation of breathing may last for at least 10 seconds, though it may last for a considerably longer period of time. Other symptoms include daytime sleepiness and morning headaches.

In the most common form of sleep apnea, the upper airway — generally above the trachea or windpipe — becomes blocked during sleep and restricts breathing. This blockage may be caused by the relaxation of the tongue and throat muscles during sleep or excess tissue that narrows the airway — often the cause among overweight people.