Innovative Sleep Solutions has released a watch called the SLEEPTRACKER (that's the official capitalization of the product). It costs $150. What makes it so special? Their website probably says it best:

When you sleep at night, your body goes through a series of sleep cycles. The average adult experiences 4-5 full sleep cycles over an 8-hour period. Each cycle lasts about 90-110 minutes and comprises five different stages.[...]

Stage 5 of sleep, also known as REM (rapid eye movement) sleep, is marked by extensive physiological changes, such as accelerated respiration, increased brain activity, rapid eye movement, and muscle relaxation. People dream during REM sleep.

For brief periods of time around REM, you are almost awake. By monitoring your sleep cycles for optimal waking moments during a set window of time, SLEEPTRACKER® finds those almost-awake moments and gently wakes you when you're most alert. The result? You wake up refreshed instead of groggy.

A review at Gear Live confirms that this product actually works. Writes the editor: "After I got up, and did the toothbrush thing, I checked the sleep data. It was very interesting to see the times that the SLEEPTRACKER had recognized as my light sleep/awake moments. Most intriguing though, was that it marked 2:11 AM as one of those moments – right after my son woke up crying!"