heh, I had that problem when I had insomnia and would fall asleep an hour before I had to wake up, which was probably worse than not going to sleep at all. Of course, I wasn't that heavy of a sleeper so I just put my alarm on the opposite side of the room which would force me to get up and turn it off.

Of course it doesn't seem that would help you out since it would awaken everyone else and not you... I do the phone thing whenever I crash at somebody elses house and need to get somewhere early, just place it in your pocket with a vibrating alarm on near the crotch area and you will wake up, guaranteed. It is scary as hell, especially knowing I get scared by a text message because my phone suddenly vibrates.

I would try the bladder one though, but this could be a bit difficult to set a time for.