Sleep apnea is the term used for periods in which a person temporarily stops breathing while asleep.

What is going on in the body?

Sleep apnea is a common sleep disorder. When a person has sleep apnea, he or she stops breathing for short periods of time. In most cases this lasts from 10 seconds to 1 minute or more while asleep. Then the person begins breathing again. A person may stop breathing only a few times or hundreds of times in the course of the night.

There are a three classifications of sleep apnea, including:

Obstructive sleep apnea is the most common type of sleep apnea. It occurs when tissue in the upper airways blocks the breathing passages. The blockage may come from a collapsed uvula. The uvula is the soft tissue that hangs down at the back of the throat. Large tonsils or other excess tissue may also block the airway. When the muscles relax during sleep, excess tissue can drop into the air passage and interrupt breathing. The person continues to try to breathe around the blockage but can't get enough oxygen. Carbon dioxide builds up in the person's blood. This problem corrects itself as soon as normal breathing is restored.

Central sleep apnea is caused by problems in the central nervous system, which includes the brain and spinal cord. In some cases, the brain may not send the message to the muscles involved in breathing. In other cases, the muscles don't receive the message because it's interrupted as it travels there, or the muscles are too weak to do the work of breathing.

What are the causes and risks of the condition?

Obstructive sleep apnea occurs when the airway is blocked by excess tissue. Seventy percent of individuals with this problem are overweight. Symptoms often improve or go away entirely if some of this excess weight is lost.

Other risk factors for sleep apnea include:

Obstructive sleep apnea occurs 3 to 20 times more often in men than in women. The women who do get it are most often past menopause.

Some of the causes of central sleep apnea include: