Definition of Obstructive sleep apnea:

Obstructive sleep apnea is a condition in which a person has episodes of stopped breathing during sleep.

See also:

• Central sleep apnea
• Sleep disorders

Causes, incidence, and risk factors:

Normally, the muscles of the upper part of the throat help keep the airway open and allow air to flow into the lungs. Even though these muscles usually relax during sleep, the upper throat remains open enough to let air pass by.

However, some people have a narrower throat area, and, during sleep, relaxation of the muscles causes the passage to completely close. This prevents air from getting into the lungs. Loud snoring and labored breathing occur. During deep sleep, breathing can stop for a short period of time (often more than 10 seconds). This is called apnea.

An apnea episode is followed by a sudden attempt to breathe, and a change to a lighter stage of sleep. The result is fragmented sleep that is not restful, leading to excessive daytime drowsiness.

Older obese men seem to be at higher risk, although as many as 40% of people with obstructive sleep apnea are not obese. The following factors may also increase your risk for obstructive sleep apnea:

• Certain shapes of the palate and jaw
• Large tonsils and adenoids in children
• Large neck or collar size
• Large tongue
• Narrow airway
• Nasal obstruction
• Recent weight gain

Drinking alcohol or using sedatives before sleep may make you more likely to have an episode of apnea.