Sleep Data Not Recording

I followed your instructions above and there was no change.  I have the same issue on my watch with "No sleep data recorded last night."  Body battery also remained flat (no charge/drain).

There was a SW update when I plugged my watch to my computer.  I installed it and restarted my watch.

I didn't want to go this route, but can you reset your device to defaults. By going into the settings on the device then remove the device from the app and it back. 

Do I need to Reset to Default Settings only or Delete Data and Reset Setting on the watch? 

mine wasn't working either, so i confirmed all my settings in the app (age height etc) turned it off and then back again and it's now working.

I also have the issue, still strugling to find out why, and how to fix it.
i have always recharged my venu 2 watched before it was at 0% battery, it happened the first time last week and it turned off. Since i turned it on, my watch does not record sleep anymore.
I connected to the computer, synced it, try to update it; i increased the sleep window even if i went to sleep after it started, and restarted the watch yesterday.
Well, it actually worked very well until i rebooted the watch; and it's difficult to test since i should fall alsleep to test it --> only 1 test a day;
does anyone knows any "trick" or workaround ? is is possible some garmin guy could watch the logs of the watch or something ? (or can i some way download the watch debug log to see if there an error message or "why the sleep monitoring does turn-on / detect my sleep " )

thanks guys

I managed to sort mine by fiddling with the “Normal Wake Time” and “Normal Bed Time” settings under User Settings and it’s worked consistently for me ever since…

Hope it helps?!

can you define "fiddling" a bit more ?

I was able to fix my issue with not recording my sleep and Body Battery by resetting my watch to factory settings a few weeks ago and I have not had issues since.

Garmin-AmberD has a case she is working for this. In the meantime what works for me is to make sure you go to the watch during the scheduled sleep hours, it will say "sleeping", tap it and choose "waking up". 

I just had this problem myself and found this thread via Google search.