Causes
There are three types of sleep apnea:
Obstructive sleep apnea (OSA), the most common type, happens when air cannot get into the lungs because the upper airway has collapsed. It's more common in men and in people who are overweight, especially those who sleep on their backs. In people of normal weight who have the condition, there's often an abnormality in the lower face, such as having a small chin, an overbite, or a large tongue. OSA typically has three phases:
- First, the airway is partly blocked as the soft tissue at the back of the throat relaxes and starts to close up, causing very loud snoring.
- Eventually, the airway collapses and airflow through it either stops totally or is significantly diminished for at least 10 seconds and up to 2 minutes.
- Finally, the sufferer wakes up briefly (although they rarely are aware of it), and often snorts or gasps for air. Once a breath is taken, the person falls back asleep and the cycle repeats itself.
Central sleep apnea, which is quite rare, results when the brain fails to send normal signals to the chest to breathe properly while asleep. Neurologic disease (i.e., disease of the brain) and severe heart disease can cause central sleep apnea, as can certain medications (especially strong pain medications like morphine and other narcotics).
Mixed sleep apnea, as the name suggests, is a combination of the first two types. It starts out as central sleep apnea, and then turns into OSA.