Its okay..

The app is pretty good but I wish there was a way to split the hours at midnight. You can set the preferences to what hours you want your day to be (6pm-6pm, or 12-12, etc) I have mine 12am-12am but if my baby sleeps 9pm-3am all of those hours are counted towards one day, not split into two.

Lalabeebear about Baby Sleep Timer, v3.1