Listing this as possible as I have been trying to identify the source of strange battery drain on my Wear OS watch. I am currently on version 20190504 beta.
After a recent restart, the battery life was good throughout the day, I then used sleep as android overnight and the next morning my battery drain was higher. At lunchtime the following day I force stopped the wear os app and my battery drain returned to the levels of the previous day.
I have been noticing strange battery results since around mid-April. I will continue to monitor this, but raising this in case it can be investigated to check that the app is properly exiting after sleep tracking is stopped on the watch.