Breathing gets too shallow or stops with sleep apnea. Each episode can last 10 to 20 seconds, and usually happens 20 to 30 times each hour.
 Obstructive sleep apnea is the most common variety of sleep apnea, and occurs when not enough air can be drawn through the nose and mouth during sleep. This causes lower blood oxygen levels, poor quality sleep, snoring, high blood pressure, heart attack, or even stroke. At least 12 million persons in the U.S. have sleep apnea, half of these are overweight, and most heavily snore. Common symptoms include: choking and gasping during sleep, loud snoring, and fighting daytime sleepiness. Most do not know they are afflicted with this condition. Diagnosis is accomplished with medical history, questioning family about how the patient sleeps and performs when awake, checking throat, nose, and mouth for possible obstructions, and recording patient's sleep performance. There are many treatments available for obstructive sleep apnea. Behavior modifications include avoiding alcohol, smoking, and medications that promote drowsiness, losing weight, and sleeping on your side to keep the throat open. Other treatments that could be required include Continuous Positive Airway Pressure, a mouthpiece, and surgery. Continuous Positive Airway Pressure (CPAP) is a mask that blows air into the throat, with the pressure keeping the throat from constricting, so the airways are not blocked. A mouthpiece can be fitted that holds the jaw and/or tongue in position to keep the airways open. Surgery can remove tissue to unblock airways to alleviate obstructive sleep apnea. Treatment is important, because sleep apnea increases the risk of unexpectedly falling asleep during the day, causing health problems, accidents at work, on the highways, and at home.