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Obstructive sleep apnea - Causes

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of obstructive sleep apnea.

Causes:

Any structural abnormality in the face, skull, or airways that causes some obstruction or collapse in the upper airways and reduces air pressure can produce sleep apnea syndrome. Abnormalities in tissues that lie between the back of the mouth and the esophagus (food pipe) are one of the most common structural causes of sleep apnea. Enlarged soft palates (the base of the tongue and surrounding throat walls) are also associated with many cases of sleep apnea.

Nerve, Metabolic, and Mechanical Abnormalities

Researchers have identified several physiologic abnormalities that may play a role in causing sleep apnea or in making it worse. These include an inability to regulate levels of carbon dioxide, impaired brain and nervous system responsiveness to various chemical messengers, and poor reflexes or muscle tone in the upper airways. The underlying reasons for these disturbances and their connection to apnea require further study.

Obesity

Obesity is strongly associated with sleep apnea and is a cause of it in some cases. Imaging scans have shown fatty cells clogging the throat tissue, which indicates that they narrow the airways. In one study, the more obese a person with sleep apnea was, the higher the pressure on the airway and therefore the greater the obstruction of the airway. (Obstructive sleep apnea may also contribute to obesity itself, however, since a sleepy person tends to be sedentary.)

Sleep Behaviors

Snoring. Chronic snoring itself may actually be a cause of sleep apnea. Over time, the vibrations and the increased pressure against the upper airways as snoring people inhale may cause the soft palate to lengthen. This stretched palate is more prone to collapse and obstruction.

It should be stressed that snoring is very common. Snoring occurs in about a third of the population, while apnea, according to one study, occurs in only 6%. Snoring, then, does not always cause apnea, nor is it always a sign of the respiratory disorder. Furthermore, while snoring is also associated with daytime sleepiness regardless of whether apneas are present, snoring alone does not appear to pose any major health risks.

Mouth Breathing. Some evidence suggests that a tendency to breathe through the mouth (rather than the nose) during childhood can actually produce structural changes in the face (longer face, narrow jaw, receding chin). Such facial characteristics may eventually put people at risk for sleep apnea.

Causes of Sleep Apnea in Small Children

Sleep apnea occurs in about 2% of children and can occur even in very young children. The most likely causes are the following:

Facial or skull abnormalities in infants.
Overgrown tonsils, adenoids, or both in small children. (Removal of tonsils or adenoids can free the airways and solve the problem.)
Premature infants also commonly have a form of apnea that may be related to lung or nervous system problems.

Resources

www.sleepapnea.org -- American Sleep Apnea Association
www.nhlbi.nih.gov -- National Heart, Lung, and Blood Institute
www.aasmnet.org -- American Academy of Sleep Medicine
www.sleepfoundation.org -- National Sleep Foundation
www.nhlbi.nih.gov/about/ncsdr -- National Center on Sleep Disorders Research
www.sleepeducation.com -- Sleep Education from the American Academy of Sleep Medicine
www.wfsrsms.org -- World Federation of Sleep Research & Sleep Medicine Societies

References

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Reviewed last on: 5/29/2008
Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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