Sleeptracker is a watch you wear while—wait for it—sleeping that monitors muscle activity and tension along with body temperature and mysterious "other signals." When those signals match the particulars of an "almost-awake" moment (the weakest points of your sleep cycle, usually around the REM phase), it can wake you up. The idea is to program Sleeptracker with the space of time you need to wake up in, and when you're closest to being naturally conscious during that span, the alarm goes off. How does it do all this? The makers ain't tellin'. For those of you leading a Fight Club-esque double life, Sleeptracker also functions as a regular water- (and blood-) resistant watch.
Sleeptracker: Waking Up Has Never Been Easier [Sleeptracker]