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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 three classifications of sleep apnea, including:

• obstructive sleep apnea, which means something is blocking the airway or the airway does not open all the way during sleep
• central apnea, in which either the brain fails to signal the muscles to breathe, or the muscles fail to receive or respond to the signal to breathe
• mixed apnea, which is a combination of obstructive and central apnea

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 cannot 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 fail to receive the message because it is interrupted as it travels there, or the muscles are too weak to do the work of breathing.

What are the signs and symptoms of the condition?

A person may stop breathing a few times a night to hundreds of times a night. The more episodes per night that the person has, the worse the problem. People with this condition often wake slightly to restore their breathing. These episodes disrupt normal sleep, which can result in extreme daytime sleepiness.

• decreased interest in sex
• falling asleep when talking, driving, or during daytime activities
• fatigue and irritability
• headaches, especially in the morning
• loud snoring
• memory loss
• mood changes
• snoring interrupted by periods of not breathing

What are the causes and risks of the condition?

• drinking excessive amounts of alcohol
• having enlarged tonsils
• having lung diseases, such as emphysema
• sleeping on the back
• smoking cigarettes
• using sleep medications

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:

• brain tumors
• central nervous system disorders
• stroke
• viral brain infection

Central sleep apnea can occur as a consequence of a stroke or other neurological disease, or sometimes as a consequence of radiation therapy for a malignancy. Sometimes, the cause is unknown.

What can be done to prevent the condition?

Weight management can prevent some cases of obstructive sleep apnea. It may be helpful for people with narrow breathing passages to have their tonsils and adenoids removed. Some cases of central sleep apnea can be prevented by preventing the associated condition, such as stroke.

How is the condition diagnosed?

Diagnosis of sleep apnea begins with a medical history and physical exam. A sleep study, called a polysomnogram (PSG), may be recommended. This test measures the following body functions during sleep:

• airflow and respiratory effort
• blood oxygen levels
• blood pressure and heart rate
• electrical activity in the brain
• eye movement
• muscle movement

A multiple sleep latency test (MSLT) measures the speed of falling asleep. An arterial blood gas test may also be performed to check levels of carbon dioxide and oxygen. An electroencephalogram (EEG) may be done to measure the electrical activity of the brain. A cranial CT scan may also be done to look for any deformities, tumors, or masses in the brain.

What are the long-term effects of the condition?

• arrhythmia, or irregular heart rhythm, which may be fatal
• cor pulmonale, or enlargement and weakening of the right side of the heart
• heart attack
• pulmonary hypertension, or high blood pressure in the arteries that supply the lungs
• stroke

What are the risks to others?

Sleep apnea is not contagious and poses no risk to others.

What are the treatments for the condition?

Treatment is focused on reducing airway blockage and increasing the amount of oxygen in the body. The first step is often a serious attempt at losing weight. It is also crucial to avoid alcohol and sleeping pills.

If these measures do not help, the person may need a continuous positive airway pressure, or CPAP, machine. The individual wears a mask over the nostrils or mouth that pumps in pressurized air. This increases the amount of oxygen entering the lungs. It also relieves the symptoms of obstruction. The technique can be used with or without supplemental oxygen.

Dental appliances may be used to reposition the tongue and lower jaw. Uvulopalatopharyngoplasty, or UPPP, is a type of surgery that removes excess tissue at the back of the throat. If all other methods fail, a tracheostomy may be done. This involves cutting a small hole in the neck through which the person can breathe.

Medicines may be needed to increase respiratory function while the person sleeps. Antidepressants may be prescribed. These reduce the amount of time a person spends in deep sleep.

What are the side effects of the treatments?

Medicines may cause stomach upset, irritability, difficulty sleeping, or allergic reactions. Surgery poses a risk of bleeding, infection, or allergic reaction to the anesthesia.

What happens after treatment for the condition?

If the sleep apnea is improved by weight loss, it's important that the individual keep the excess weight off. Some treatments, such as the use of a CPAP machine, are lifelong.

How is the condition monitored?

Any new or worsening symptoms should be reported to the healthcare provider.