Majoru Oakheart
Adventurer
I disagree. Resting at night generally proves to be not dangerous at all in most situations. You fight until you are at half health and spells. Then you rest for the night knowing you have the second half of your spells and hp to survive anything that would attack you at night. Then you wake up with full HP and spells again.Further, I think the idea is completely unnecessary. There's already ways of making resting in dungeons dangerous, the easiest of those is the possibility that the party will be ambushed at night. Capping the hp that can be regained by resting in such situations is an annoying rule that really adds nothing to the game but takes a lot away. They need to abandon this terrible idea.
This is the way my games have gone for the longest time(basically every game post 2e). Even if you didn't regain ALL your hp from sleeping, healing spells were powerful enough that you'd just use your leftover spells before you went to sleep to heal everyone to full.
I suspect people might be a little less likely to rest in the middle of the dungeon if there was the risk of damage that didn't heal from anything that attacked you in the middle of the night.
Whether you like the idea of people sleeping in dungeons is another story all together. If you like that idea, this will definitely discourage it.