To edit a sleep session that you have already saved, tap on Reports at the bottom of the screen. Then tap on the sleep session you want to edit. When you do, details about that sleep session will show up at the bottom of the screen. Tap the details section with the “>” for Edit and Delete options.
You can also access this from the List view in Reports.
To edit, tap on the “Start” or “End” times and use the time picker to adjust the times. You can also change the sleep details.