If trying to set ending sleep time after 00:00 my watch says "schedule overlap" and have to choose a new ending time. For example, setting sleep from 21:00 - 00:01 is not possible. Yesterday I had the same problem and after checking my sleep data the watch had added 12 or 24 hours to the time I was sleeping. Had to remove the extra hours in GC. I fear that this will happen with all new sleep data from now on. My date and time is correct on my watch and I have tried to reboot it without solution. One clue (before I got this problem) is that I one evening when the watch was in sleep mode I changed the sleep schedule with a few hours to be awake a little longer. The watch was no longer in sleep mode after, but I could see that it still was measuring pulseOX (red light) which it is set to only do during sleep. Because of this I rebooted the device and it was no longer checking pulseOX (good). Guess I found a bug?