I usually don't have this problem, but when I'm REALLY tired I do tend to screw around with my alarm clocks and either oversleep or fall back asleep for a few minutes and then wake up having a heart attack because I think it's noon. Usually this happens because I was up all night preparing for something big, so it's imperative that I get up on time... here's what I do:
I use my cell phone as a regular alarm. It's got 4 different alarms you can program in and most do, so set that to whatever you like. I keep it plugged in and right next to my head on my bed.
I have another alarm clock for those 'special occaisions' where I can't afford to over sleep. I put it on my laptop (since I rarely use it and my neighbors would not appreciate if I left it to go off all morning while I showered). I always check my email first thing in the am, and it's far enough away that I have to get my butt out of bed to turn it off. Usually what I do is set the cell for, say, 5:50 am. Then I set the real alarm clock for 6:00. If all goes according to plan, I wake up, turn both off, and go on with my morning. If I somehow turn off the cell, then the other one wakes me up and I have to get out of bed to take care of it. I also panic and get a little adrenaline rush by realizing that if it's going off, it means I'm already running late heh