Display duration till next alarm

From Anonymous on 2017/01/10 21:42:14 +0000

I would like to see how long (hh:mm) i can sleep till next alarm after starting the sleep tracking.
Today i see the current time and the alarm time so i have to calculate the remaining time on my own.

Copied from original feature request: http://urbandroid.uservoice.com/forums/264867-sleep-as-android/suggestions/17685610-display-duration-till-next-alarm