"Fall Asleep Hour"

The one statistic I do not understand is called “Fall Asleep Hour.” Is this the exact time you start tracking, or is it when the app first detects sleep rather than “wake.”

If it is the latter, would it be better to let it detect sleep automatically, or to do what I always do, which is to push the button?

Thanks for the clarification.


I really would like this explained. So I can start tracking earlier and not disturb the statistics if “Fall Asleep Hour” is different than the start-tacking time.