What Is Obstructive Sleep Apnea?

Obstructive sleep apnea (OSA) is a debilitating and often life-threatening medical condition. It is the most common type of sleep apnea.

When a healthy person sleeps, the muscles of the upper part of the throat allow air to flow into the lungs. However, when a person with OSA falls asleep, these muscles are not able to keep the air passage open all the time. When the airway closes, breathing stops, oxygen levels fall, and sleep is disrupted in order to open the airway.

The disruption of sleep usually lasts only a few seconds. However, these brief arousals interfere with sleep and prevent people with OSA from reaching the deep stages of sleep, such as rapid eye movement (REM) sleep, which the body needs in order to rest and replenish its strength. Once breathing is restored, people with OSA fall asleep only to repeat the cycle throughout the night.

Obstructive sleep apnea occurs when the muscles in the back of your throat relax too much to allow normal breathing. These muscles support structures including the soft palate, the uvula — a triangular piece of tissue hanging from the soft palate, the tonsils and the tongue.

When the muscles relax, your airway narrows or closes as you breathe in and breathing may be inadequate for 10 to 20 second, or longer. This may lower the level of oxygen in your blood. Your brain senses this impaired breathing and briefly rouses you from sleep so that you can reopen your airway. This awakening is usually so brief that you don't remember it.

You can awaken with a transient shortness of breath that corrects itself quickly, within one or two deep breaths, although this sequence is rare. You may make a snorting, choking or gasping sound. This pattern can repeat itself five to 30 times or more each hour, all night long. These disruptions impair your ability to reach the desired deep, restful phases of sleep, and you'll probably feel sleepy during your waking hours.

People with obstructive sleep apnea may not be aware that their sleep was interrupted. In fact, many people with this type of sleep apnea think they slept well all night.