Causes of Obstructive Sleep Apnea (OSA)

In some people, sleep apnea is the result of a central nervous system abnormality that interferes with the normal instinct to breathe. In others, it results from a collapse and blockage of the upper airway during sleep, due to anatomical factors (such as large tonsils) that narrow the upper airway, excess fat in the tissues around the throat, or an enlarged tongue.

A large neck or collar size (more than 17 inches in men or 16 inches in women) is strongly linked to sleep apnea. Some people have both the anatomical and the nervous system causes at the same time.

Obesity, older age, weakness of the airway muscles, smoking and hypothyroidism are additional risk factors for sleep apnea. Consuming alcohol or sedatives before going to sleep can further reduce the activity of the airway muscles.

Symptoms of Sleep Apnea

The most pervasive and troublesome symptom of sleep apnea is excessive daytime sleepiness caused by poor sleep at night. People with sleep apnea may fall asleep during the day while reading or even while driving, so there is a major risk of motor vehicle accidents. They may also suffer from memory loss and personality changes. Although loud snoring is a common sign of sleep apnea, snoring itself does not indicate obstructive sleep apnea.

More than half of those with sleep apnea also have high blood pressure, and their blood pressure does not fall during sleep as it does in most people. In fact, sleep apnea has been shown to be an independent, treatable cause of high blood pressure. Research suggests that sleep apnea also doubles the risk of stroke in some people.

The heart rate tends to slow dramatically during periods of apnea and then rise rapidly when breathing resumes. Some evidence suggests that periods of apnea and the resulting low levels of oxygen in the blood, along with persistently high blood pressure, increase the risk of coronary heart disease and blood glucose intolerance. Researchers are currently studying these links.

Sleep Apnea Diagnosis

Obtaining a sleep history is key to recognizing sleep apnea. Input from a bed partner can be especially important, because the partner is likely to notice snoring associated with frequent periods of apnea.

Definitive diagnosis usually requires spending one night in a hospital sleep laboratory to undergo polysomnography, a set of sleep studies that monitor brain waves (to determine which stages of sleep are associated with episodes of apnea), heart rhythms, airflow and breathing patterns, eye and leg movements and blood oxygen levels.

Some people may be able to undergo monitoring at home using portable equipment. A sleep specialist can perform an evaluation to determine if you're a candidate.

Publication Review By: Peter B. Terry, M.D., M.A.

Published: 09 Aug 2011

Last Modified: 27 Feb 2015