Interesting you mention you had this problem. Almost the exact same thing happened to me just the other night. I was right at the point where I was about to fall asleep but I knew I wasnt sleeping yet. I couldnt move at all and after a few minutes I lifted my head up, looked at the clock and three hours had gone by. I was very disoriented and fell right back asleep. Maybe you had actually slept? You ever woke up an hour before your alarm was supposed to go off, you fall back asleep, and you hear your alarm going off and it seems like you had only slept for 2 minutes.
Since its only happened a few times I would'nt worry to much. If the problem persists definately tell your doctor. If you do goto a doctor describe your exact problem to them. I dont know how it is in Canada but here in the states if you goto your doctor and tell him your "having trouble sleeping", he'll probably put you on anti-depressants, thats doctors answer to everything. Although if you do have alot of stress in your life: work, girlfriend, school, etc, it can cause sleeping problems.
And ofcourse, as others have mentioned: Drugs. I know I've been around a few people, years ago, that were afraid to sleep with the notion they were'nt gonna wake up if they did fall asleep.
2.0 Bearded Dragons