Any kind of device that has a "single beep" alarm or something similar? (I know my old ipod-nano's alarm sucks, as it just beeps once then is done. But it is perfect for waking up in the middle of the night) If not, do as they said and either drink allot of water, or practice a mantra. Mantras are basically going over a thought in your head over and over before bed, such as, "I will wake up in 4 1/2 hours." Personally, almost never works for me, but seems to work quite well for many other people as your body will actually listen.