My brother-in-law invented this concept at least three years ago, maybe more (so he would have been about 15). In his case, it was an alarm clock that would track your sleep cycles by recording your brain waves, and wake you at the most opportune time.
The Sleeptracker watch is #1 on my list of most wanted gadgets that I can’t afford right now. I wish I had a birthday or something coming up; I’d get all of my family to go in on it together. February’s not that far away, is it?