How about a timer switch attached to your light?
Me personally, I've been waking up at 5 am for so long now that as long as I'm in bed before 11:30 I know I'll wake up before my alarm, sometimes I can even stretch to midnight; although Ideal is 10:30-11:00
In your situation I would try and make it light rather than noise, I don't like the full bladder trick because that will just make you uncomfortable :-(
Although the guy and a stick idea might work :-D