German company Ageye has developed an Alarm application for Windows
phone 7 users. What special this apps having : G-Alarm has to be
running to wake the user up, but it also means Ageye was able to ad
the ability for the app to monitor your sleep and let it wake you up
when you’re in a light sleep phase.
for more info :
http://yobif.com/mobile-news/g-alarm-for-windows-phone-7/