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 the person stops breathing for at
least 10 seconds and up to 2 minutes.
- Finally, the sufferer wakes up briefly (although they rarely are aware
of it), struggling to breathe, snorting or gasping for air. Once a breath
is taken, however, the person falls back asleep and the cycle repeats itself.
Central sleep apnea, which is quite rare, results when the brain fails
to send signals to the chest to breathe properly while asleep. Here too, however,
the person ends up waking up repeatedly during the night to breathe.
Mixed sleep apnea, as the name suggests, is a combination of the first
two types. It always starts out as central sleep apnea, and then turns into
OSA.