Causes of sleep apnea

What causes sleep apnea

There are two main reasons why sleep apnea occurs: airway obstruction or a disconnect between your brain and your body.1 Airway obstruction is by far the most common type, causing the symptoms of obstructive sleep apnea (OSA).

A disconnect between your brain and body causes central sleep apnea. Some people have a combination of both types of sleep apnea. (Mixed or complex sleep apnea).

What's happening in my body?
Obstructive sleep apnea
When you go to sleep, your throat and tongue muscles relax. This can cause the soft tissue in your mouth and throat to fall back and obstruct your airway.2 Blocked nasal passages can also contribute to the problem. The obstruction stops you from breathing properly causing your oxygen levels to drop.

After about 10 seconds, your brain detects the low oxygen level and sends a signal to your body to wake up and breathe. At the same time, your blood pressure spikes.

You wake up and take a deep breath, then go back to sleep.

This can be repeated many times a night without you even noticing.
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Central sleep apnea
With central sleep apnea, your airway is not obstructed, but your brain isn't sending the normal signals to your body to tell it to breathe.

Your breathing stops for 10 seconds or more. During this time your body makes no effort to breathe.

It's quite likely that you don't snore with central sleep apnea.3

Central sleep apnea may be caused by certain prescription painkillers. It may also be brought on by high altitude or by a medical condition such as cardiovascular disease, stroke, infection or neurological disease.
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Obstructive sleep apnea causes4

  • Sleeping on your back. If you sleep on your back, the relaxed muscles in your mouth and tongue can restrict your breathing
  • Thick tissues at the back of your mouth. A piece of tissue called an 'uvula' hangs down from the top of your mouth. When you go to sleep it can slip back and obstruct your breathing
  • Enlarged tonsils and adenoids can also restrict your airway and cause obstructive sleep apnea
  • If you're overtired, or suffering from lack of sleep, when you do finally sleep, your muscles relax more and this can contribute to obstructive sleep apnea
  • Allergies, hayfever, colds, sinus infections and flu can block your nasal passages and contribute to sleep apnea
  • Overweight people often carry extra fatty tissue around their neck area which increases the restriction of their airway when they sleep

Central sleep apnea causes5

  • Weakening of your breathing reflex. This can occur in people who have had obstructive sleep apnea for a long time
  • Slow blood circulation due to heart failure can affect your normal breathing reflexes
  • Certain pain medications can reduce your urge to breathe, e.g. morphine
  • A stroke or other brain problem can affect the part of your brain controlling breathing
  • Weak lung muscles brought on by a neuromuscular disorder
  • A chest wall or lung abnormality may have caused your lungs to be too stiff
  • High altitude causes central sleep apnea in some people6



Source: Harrington, C. The Complete Guide to a Good Night’s Sleep. Pan MacMillan Australia 2014.