It could also be classified as "Lucid Dreaming" but in any case, that would suck.. The human body has certain "Protections" for things are about to "Kill" us in our sleep. If you've ever had a dream where you are about to die, you always wake up at the exact moment you are going to die. It's one of those things that you really can't explain, but it's your bodies way of telling you "your in trouble, WAKE UP" I'm trying to find some articles about people who have actually died in their dreams, and in turn died in real life. I personally can't say it's ever happened to me, but then again, I don't remember most things that happen to me...
That happens to people with sleep apnea or however you spell it. People who have trouble breathing when they sleep. So when they are asleep and can't breathe a dream like that may occur