I would like to add that many people have sleep apnea and don't even know it. It reduces oxygen greatly at night. And you can't guess that you have it either, you have to be tested. Being overweight, snooring loudly and stopping breathing during sleep are not signs you can always count on to prove you have it. I didn't do any of those things but my doctor found that I had extremely large tonsils that interfered with my breathing at night.