Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Sleep Apnea

What Is It?

Sleep apnea is a disorder that causes people to stop breathing for short periods during sleep. These periods are called apneas. Apneas usually last between 10 and 30 seconds. In severe cases, apneas can happen many hundreds of times each night. People with untreated sleep apnea are more likely to develop high blood pressure.

Apneas disrupt a person's ability to get a good night's sleep, making them less alert during the day. This can lead to accidents. People with untreated sleep apnea are up to seven times more likely to be involved in motor vehicle accidents.

There are two types of sleep apnea:

• Obstructive sleep apnea occurs when the airway in your nose or throat becomes partially or completely blocked. It can be blocked by large tonsils, a large tongue or by too much tissue in the airway. Excess tissue in the airway is more common in people who are overweight. When airway muscles relax during sleep, this extra tissue can block the breathing passages.

• Central sleep apnea occurs when the brain stem, the area of the brain that controls breathing, is damaged. The brain stem may be damaged by an infection or stroke.