The exact cause of OSA remains unclear. The site of obstruction in most patients is the soft palate, extending to the region at the base of the tongue. There are no rigid structures, such as cartilage or bone, in this area to hold the airway open. During the day, muscles in the region keep the passage wide open. But as a person with OSA falls asleep, these muscles relax to a point where the airway collapses and becomes obstructed.
When the airway closes, breathing stops, and the sleeper awakens to open the airway. The arousal from sleep usually lasts only a few seconds, but brief arousals disrupt continuous sleep and prevent the person from reaching the deep stages of slumber, such as rapid eye movement (REM) sleep, which the body needs in order to rest and replenish its strength. Once normal breathing is restored, the person falls asleep only to repeat the cycle throughout the night.
Typically, the frequency of waking episodes is somewhere between 10 and 60. A person with severe OSA may have more than 100 waking episodes in a single night.
Physician-developed and -monitored.
Original Date of Publication: 01 Dec 2000
Reviewed by: Stanley J. Swierzewski, III, M.D.
Last Reviewed: 04 Dec 2007
Obstructive Sleep Apnea (OSA), Sleep Apnea Causes reprinted with permission from sleepdisorderchannel.com
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