Hell, someone might call it a "psychic wake-up-call".
When you tell yourself bad enough you want to wake up at a certain time, you're going to. Your Higher Self wakes you up at the right time.
Or your subconscious mind feeds information from outside (ticking of clocks, passing of time) to you and wakes you up at the appropriate time.
Either that or you're a bunch of hippie freakes. There I said it. 
tah tah
PS. for your psychic wake-up-call check out William Hewitts book Psychic Development for Beginners
Ste