I seem to have a weird bug in my new saves since the "Meep Recreation Pack" update and that is that when downtime ends, if they are in a beach chair they will just stay in it and not go to bed. In the screenshot you can see my dupes who are supposed to be in their beds tanning away with about 38% stamina for the new day.
All my dupes have a 5 shift break and 3 shift sleep
This causes the obvious problem of giving all of the dupes who have been sunbathing, temporary narcolepsy where they will just fall asleep at the end of their stamina often times somewhere dangerous, with maybe no oxygen left in their atmo suit. Inevitable result, duplicant death.
Build some beach chairs and monitor duplicant sleep for those using it.