If a party stays overnight in the dungeon or the wilderness, do they heal at all? The rules say a person with a full day's rest in reasonable conditions heals 1d3 HP. But what if they just get an uninterrupted night's sleep in a dungeon setting? Saying that it's worth 0 HP seems to make delves away from "home base" functionally impossible without magical healing or 2 levels of Healing proficiency.
Until I hear something official, I have temporarily house-ruled it that they get 1 HP back for an uninterrupted night's sleep.
If they actually managed to rest for 8 hours in a dungeon, I'd let them heal 1d3 HP, but most dungeons still have random encounters so they'd have to have found a secret room to post up in or somehow barred a door.
The rules make references in the healing proficiency to added benefits for complete rest, which I think is in contrast to your standard 8 hours of rest.
Doesn’t a “full day” mean 24 hours? I’d say they might get 1 hp from sleeping in a dungeon, but 1d3 seems too much btb.
I would say yes, a full day "in reasonably sanitary conditions" is the prerequisite for 1d3. Normally I'd give 0 for anything less, but in the right campaign 1 hp for uninterrupted sleep seems fine.
I typically do 1hp for a night of rest in a dungeon with a healer present. I should add that to my list of house rules!
Does the extra d3 per day from healing proficiency also need full bed rest to work, or can it be applied during an adventure?
You need the bed rest. The healer can use his Cure Light Wounds ability, though.