Explore the Causes of Sleep Apnea

Being overweight or obese.

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Sleep apnea can have many potential causes, most of which relate to problems with the anatomy of the upper airway. Sleep apnea is a chronic medical condition where the affected person repeatedly stops breathing during sleep. These episodes last 10 seconds or more and may occur hundreds of times during the night. The resulting dropped oxygen levels of the blood can lead to significant sleep disruption and serious consequences. It may occur secondary to obstruction of the upper airway, resulting in obstructive sleep apnea, or because of a failure of the brain to initiate a breath, called central sleep apnea.

Being overweight or obese is perhaps the major predisposing factor for sleep apnea. Being overweight likely contributes in two ways. First, when you are overweight extra fat tissue will build up throughout your body, including along your airway. This may lead to some narrowing -- especially in the throat -- that could make it more prone to obstruction while you sleep.

In addition, the extra pounds may serve as an external pressure that accomplishes the same thing. Imagine a 30-pound bag of sand sitting on your chest or stomach. It’s no wonder that this extra weight can disrupt your breathing. Individuals with large necks are especially at risk for apnea because the pressure is more direct.

Having abnormal anatomy of the upper airway.

The lower jaw, or mandible, is illustrated in red. SCIEPRO/Science Photo Library/Getty Images

There are multiple abnormalities of the upper airway that may make it more likely to collapse or become obstructed and result in sleep apnea. Some people are born with abnormalities of their face, mouth, or throat that make it easier for the airway to close. Certain craniofacial malformations, including a condition of hypoplasia or underdevelopment of the midface, may contribute. More common issues such as enlarged tonsils or adenoids may cause the airway to be smaller than it should be. This is a significant cause of sleep apnea in children. In addition, a small or recessed jaw (called retrognathia) or a large tongue (termed macroglossia) may likewise be problematic.

Using medications, drugs, or alcohol that relax the upper airway.

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Even with a normal airway, it may not stay that way if you pursue certain indulgences. The use of alcohol can relax muscles that will make the upper airway more likely to collapse. This may also occur with the use of sedatives, including sleeping pills or medications like benzodiazepines. Other narcotic medications, which are used for pain relief, may also lead to sleep apnea.

Losing muscle tone with aging.

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Sleep apnea is far more common among the old. It occurs in about 7% of adults and nearly 25% of the elderly. What causes this? As we age we lose muscle tone, including within the muscles of our upper airway (especially the throat). This more relaxed airway is easier to obstruct while we are asleep. This can have serious consequences, making common medical conditions like high blood pressure and diabetes worse, as well as leading to stroke and sudden death.

Sleeping on your back and dreaming.

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You may have been told, “You only snore when you sleep on your back.” The same may be true for the occurrence of sleep apnea. This may lead to frequent, carefully placed elbows during the night in an attempt to get you to turn onto your side. The most likely cause is the tongue or soft palate shifting into the airway due to gravity or excessive weight in the upper body causing the airway to collapse. When you sleep on your side, this weight isn’t pressing back onto your throat.

In addition, many people have more frequent sleep apnea during dreaming or REM sleep. This likely relates to the muscle relaxation that occurs during REM. This phenomenon is meant to prevent you from acting out your dreams, as may occur in REM behavior disorder, but it also makes your airway more likely to collapse.


Mowzoon, N et al. “Neurology of Sleep Disorders.” Neurology Board Review: An Illustrated Guide. 2007; 725.

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