Sleeping in a subway station in mid-summer with just your mouth uncovered and dry causes you to freeze to death in your sleep. about cataclysm-dda HOT 4 OPEN

OK there is some interesting things going on here, all resolving around Character::update_bodytemp()

First up, your light eater trait is causing you to lose temperature.

Removing that alone takes you from -39 displayed mouth warmth to -25. Lower metabolism resulting in lower overall body temperature makes sense in a biology/mutation context, but not "I picked light eater in chargen" sort of way.

But the big killer is that it depends on how tired you were.

0 sleepiness, no light eater:

900 sleepiness (exhausted), light eater:

And you won't wake up unless your torso is in the danger zone:

from cataclysm-dda.

I'm pretty sure this is a very old bug and has gotten me a couple of times. I've noticed it particularly hitting when I was sick with a cold, though that may just be a coincidence. There's a lot of weird hardcoded stuff with cold/flu though, so it's possible something strange is happening there.

A couple of years ago, shivering was added which was supposed to prevent you from falling asleep while cold. This never worked right, and just made it impossible to sleep at all even in safe (but chilly) temperatures for a long time. Eventually this got "fixed" such that it was once again possible to freeze to death in your sleep. Better, I guess, but only because it's the sort of thing you can usually savescum around.

There's also some code involving limb HP and cold which should probably be removed. Limb damage reduces effective temperature on that limb which used to be a stand-in for things like blood loss, but now that we actually have hypovolemia, it no longer makes sense. That code should also be excised as it can cause bizarre things like having your legs break while you're asleep because it was 40 degrees and they were at half HP when you nodded off.

Mouth coldness is a weird idea and probably shouldn't be able to cause actual HP damage to the player. Yes frostbite exists and the nose is one of the places it can happen, but a fully bundled up guy is not going to die of hypothermia because his nose got frostbitten. Maybe mouth coldness should stop dealing HP damage until a wound system is added, at which point a frostbitten nose/mouth would be more dangerous due to the infection it would lead to.

At the very least, for hypothermia (which I assume is what head/torso damage from cold is trying to model), the mouth and head could be averaged rather than tracked separately.

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this bug report seems relevant. might not be a direct duplicate, but it definitely has some overlap (freezing head damage to sleep death) #72798

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After some digging, I found this post. So having both light eater and recycler unit is why I'm freezing to death in a 6C basement. A few thoughts:

1. Some extra tooltip? Might well write it myself, but I'm not that fluent in english.
2. Should recycler unit affect metabolism (by extension, lower body temperature) at all? Doesn't fit the description, what with "reclaiming waste liquid and nutrients" and such.

In the meantime, I'm going to try my luck with a JSON-based dirty "fix".

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