From time to time, I engage in what can be described as “buying toys destined to collect dust on shelves.” Skipping the psychoanalysis of why I do it, I usually recognize when I’m trapped in that mode, which helps a towards breaking the cycle, but I still end up with some momentos. The SleepTracker Pro might be one such.
The company website promises to “Say goodbye to blurry mornings!” and talks in laymen’s terms about the sleep cycle and how the key is to be woken up at the point in the sleep cycle where one is nearly awake anyway.
Naturally, I was skeptical at first, but it reviewed well (e.g. Wired) and received favourable commentary on Amazon. It is ridiculously expensive for what appears to be an ugly, but otherwise normal digital watch. However, curiosity eventually beat out good sense (also refer to frivolous-gadget-buying-mood above) and the watch duly arrived.
Does it work? Yes, in a fashion. Particularly the first few days, I was impressed by how much it did not suck. It really did wake me up at times when I was half awake. I would groggily turn over and nearly fall back into slumber when it would trigger, and only after waking did I realize that how close I had come to waking and going back to sleep. Remembering to wear the watch to bed wasn’t troublesome at all, and of course I didn’t notice it all when asleep.
The watch seems to be a simple accelerometer: it can sense when it’s moved, like a pedometer. As you sleep, it maintains an average on how often you move your arm. It uses that average to “guess” when it should wake you up, i.e. +/- X minutes around your target wakeup time. It uses a mild beeping sound, and can be set to vibrate, too. Vibration with no sound is a surprisingly relaxing way to wake up.
The downsides? Other than the cost (rip-off, really), it’s easy to sleep through the mild beeping and/or vibrations. Also, if you don’t move much in your sleep, or you’re pinned down somehow (e.g. lots of pillows on the bed, hugging a body pillow), it won’t work very well because it assumes some arm movement when you’re in “light” sleep.
As I have to “set” the watch so that it knows when I’m going to bed each night (just hold down a button), one unexpected “benefit” is that I have to give a long look at what time I’m actually sleeping. As the product manual says, SleepTracker isn’t a substitute for getting enough sleep… but the guilt it helps create might be beneficial towards that. 
