I didn't explain it very well. As Singdaw says it isn't necessarily waking up, but you stop breathing, in my case now, 1 or 2 times an hour (without the CPAP machine it would be around 10 to 15 times an hour).
Although when you start gasping for air that does often wake you up, but you are so used to it that you don't remember waking up. Anyway, you never get into a deep sleep like other people do. And I would always wake up with a headache from lack of oxygen to my brain.