Can you get randomly murdered in your sleep? Like theoretically, a fox could kill you if he found you asleep at a shelter, no?
Kind of a necro to provide a data point on one of the questions in the very first post in this thread:
Yes, you can get killed randomly in your sleep by an animal.
It has happened to one of my characters in the butt-naked stage. Here is a Ancestors screen screenshot:
This was with 'Hurt, Helpless and Afraid' scenario, having spawned with not-much, I started collecting slender trunks, to produce javelins. At the end of the day I made a waterside shelter and slept there and I completely ignored the fresh bear tracks in the area (what can go wrong, right?). Then I got a message saying that I have been killed (in my sleep). GG, I guess.
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Edit: Just adding here another case, in case a new player sees this post... There is no protection in a "shelter" against bears/wolves etc. however in a wooden cabin, you will be protected from wolves etc. but there is one exception, bears can still open the door, let themselves in and then kill you.
This cabin invading bear event also happened to me in the past and also once more very recently but the last time I was in full dark green armour with 7 dogs around cabin and 3 bulls tied to me so it only got a chance to get killed very fast. I am adding a screenshot below.
Do note that, while I have a much larger cabin, in this instance, I decided to sleep in the tiny sauna which in hindsight was a mistake because due to the limited physical space inside invading bear's had the ability to block the door and still reach me while getting attacked by lesser number of my hairy companions.
Had I slept in the larger cabin and at least 2 tiles away from the door, bear would have to move away from door to attack me, unblocking the entrance, letting more of the 7 dogs (in addition to 3 bulls) attack him each turn which would have killed him even faster.