During awake the throat muscles keep the airway stiff, and open so air can flow into the lungs freely. However, during sleep, these muscles are more relaxed. Still, these relaxed throat muscles cannot stop the airway from staying open in the case of healthy individual.
What causes sleep apnea?
However, if having obstructive sleep apnea, the airways are blocked or narrowed during sleep, because:
- Throat muscles and tongue relax more than normal.
- Tongue and tonsils are larger than normal than restrict the opening into the windpipe.
- Being overweight, the extra soft fat tissue causes the inside opening to narrow and makes it harder to keep open.
- Head and neck bone structure may cause a smaller windpipe.
- Aging losses the ability of brain signals to keep the throat muscles stiff during sleep. Thus, the airway will narrow or collapse.
Not enough air flows into the lungs when the airways are fully or partly block during sleep. This can cause loud snoring and a drop in the blood oxygen levels.
When the oxygen drops to dangerous levels, then it triggers the brain to disturb sleep. It helps to tighten the upper airway muscles and open the windpipe. Thus normal breath starts, mostly with a loud snort or choking sound.
The frequent drops in oxygen levels and reduced sleep quality trigger the release of stress hormones. It raises the heart rate and increases the risk for high blood pressure, heart attack, stroke, irregular heartbeats and also raises the risk for or worsens heart failure.
Untreated sleep apnea also can lead to changes in how the body utilizes energy and thus increases the risk for obesity and diabetes.