Sleepy Clock is a sleep cycle calculator for your Windows Phone. What is a sleep cycle calculator you ask?
A sleep cycle is 90 minutes long and in general, you need 5-6 cycles to be well rested. Sleepy Clock goes about calculating the amount of sleep you need to be well rested from two approaches.
First, you can enter the time you need to wake up and Sleepy Clock will show you a range of times you should try to fall asleep at to get enough rest. Next, if you are about to fall asleep you can see a range of times you'll need to wake up at to be well rested.
In calculating your wake up time, if you tap on one of the times displayed you will have the option to set your Windows Phone alarm from within the app.
There's really not much to Sleepy Clock but it does what it does well. A log to keep track of your sleep history would be a nice addition but if you're looking for a simple, straight forward app to help you manage sleep cycles it is worth at try.
There is a free trial version (with ads) for Sleepy Clock that lacks the ability to set your Windows Phone alarm within the app. The full version (ad free) is currently running $.99 and you can find it all here at the Windows Phone Marketplace.