Check out Sprout Baby before you buy this app. For $4.99 it includes Sprout Sleep plus a lot of other features. My advice: start with the free version, it lets you test the full app (including the Sprout Sleep tool!) for 14 days.
Note my review concerns the cost of the app not its functionality. I would give this a better review if I didnt feel like I just wasted money.
AB437 about Sprout Baby Sleep Tracker