Originally posted by PakaNoHida:

I do not believe this at all.

Mobs do not spawn in rooms with closed doors
The game tells you and prevents you from sleeping if mobs are near.

Since it’s very likely he was killed by a swamp event, he went to bed before the event started and then the mobs spawned as he was falling asleep, which would allow them to enter his house and camp at his bed (Mobs do spawn and can move while sleeping). It’s likely a combination of bad luck and poor house coverage with core structures so that there was spaces that mobs could spawn in/near his house.