Is it possible?

I was wondering whether it is possible to develop an application that utilizes the accelerometer of N95 phones to detect and track the sleeping phases of the person wearing the phone on his wrist.
The idea is already popular, and the 140$ product is called Sleeptracker. and another variation of it can be found Here .

Tracking sleep phases has also other benefits, among them is the idea of stimulating Lucid Dreams by signaling to the user when she gets into the REM phase of sleep (the dreaming phase), the signal will be detected by the dreamer's mind and allows him to become lucid. A 250$ similar device is called NovaDreamer uses the same concept is popular in the market..