Add ability to Auto-Start Sleep Tracking at preset intervals

From K S on 2015/06/04 18:29:17 +0000

I would like to see the ability to set the sleep tracking feature to start ‘X # of hours’ (preset or fill-in values) before alarm time. I always forget to start the sleep tracking manually so it’d be nice to not have to worry about that.

Copied from original feature request: