What is the coldest temperature a human can survive in without clothing?

Let’s say you’re inside an empty, windowless room that can somehow maintain a specific temperature all the time. Whatever heat your body radiates into the environment is removed quickly.

If you’re standing in there completely naked, how cold could it get before you would die in the long term? Assume you have plenty of water and food.

Clearly there is some temperature at which the air is robbing your body of heat more quickly than it can be produced, but what is that temperature?

I suppose it depends on how long you have to get used to it.

Magellan remarked on how the natives of Tierra del Fuego walked around naked in a climate where it rarely got above 50 degrees Farenheit in the summer (cite).

On the other hand, hypothermia usually develops between air temperatures of 30-50 degrees (cite). Assuming one is dry, and there is no wind, I suspect you would begin to develop symptoms closer to 30 degrees than 50. Much depends on how much insulating subcutaneous fat you are carrying, and how active you can stay. Also what the floor is made of - a bare stone floor is going to conduct heat away from you better than carpet. If the water that you drink is colder than body temperature, that will also affect how fast you cool off.

At a rough guess, an un-acclimatized person with normal levels of body fat, in a room large enough to allow walking and with an insulated floor, could survive temperatures in the 40-50 degree range as long as he/she was able to keep moving. Ultimately, s/he would be exhausted and hypothermia would begin to develop.

I suppose it is inevitable to point out that you are not the first person to ask the question, or one like it.


“…Ultimately, s/he would be exhausted and hypothermia would begin to develop…”

THAT, is the key.

My guess, 60F would be about the minimum a naked person could exist in for any length of time. IF, they were not required to sleep on a heat-sink surface.

There are anecdotal stories of “the hole” in Alcatraz. The prisoners were practically naked in a steel and concrete cell. They never slept for long periods of time; needing to move about often to maintain warmth.

If you are also interested in the coldest temperatures a person can survive in without clothing for short periods, I think there is a “100 Club” of people who have visited the South Pole and have run, naked, out of the building, to the pole marker and around it a few times, and back, all while the temperature is less than -100 F.

I read once that native Australians slept essentially naked in temperatures that could get down to 40F. For myself I would start to shiver in 68 deg without pyjamas and a good blanket. But I guess if you have enough food, the body will eventually start producing enough heat to keep you alive (if not comfortable). Remember though, that the Australian climate tends towards extreme heat, especially in the north. Just for the record, the city of Sydney itself has never recorded a frost (although inland suburbs have).

[nitpick]Assuming you mean this literally, the temperature is going to be pretty close to 98 degrees. If all heat radiated off your body is quickly removed, your body will very soon reach equilibrium with the environment. You can die of hypothermia in 85-degree water. (It’s not easy, but you can do it – the water would have to be moving for starters.)[/nitpick]

Anecdotal as all hell, but according to my trusty desktop thermometer, it’s 38.1 F in my apartment right now. I’m in boxers, and my current activity level consists of moving my fingers to type this post. I have an about-average body composition. I’m doing just fine; I do this regularly in the wintertime with no ill effects, and were I somehow superhuman, I’d hope my doctor would have noticed by now. (I do, however, have a sheet and comforter on my bed for when I go to sleep; I have to imagine I’d be in trouble otherwise.)

It’s a data point, if not much else.

There is a link to metabolize.
If one has a hyper active thyroid it is believed they will tolerate lower temps.
There must be studies with Eskimos?

In the fall when the temps drop to 40 (F) we struggle with keeping warm, Then in the spring after -10 to -40 (F) through the winter and we get to +40(F) we rejoice and feel we could live forever at that temp and never get cold again:dubious:

>If all heat radiated off your body is quickly removed, your body will very soon reach equilibrium with the environment.

Randy, I took this point to mean that whatever heat energy the body did radiate away was quickly dissipated further away in the environment and did not warm the environment significantly. That is, the rate at which the energy was radiated would be its normal rate for those conditions, but the environment wouldn’t change as a result.

Uhm, why on earth is it that cold in your apartment? I have my doubts that the average person could withstand 38 F degree temperatures in boxers only and not be shivering and extremely uncomfortable. Either you’re not average, or your thermometer is terribly miscalibrated.

Another totally anecdotal data point:
I lived in Alaska for 16 years.

After a couple of years of residence, when breakup came and the temperature reached 40, my whole family (and everybody in the neighborhood that wasn’t at work) would be outdoors all day in short shorts and tank tops, barefoot. The tank tops were optional on the guys. If it had been socially permissible, I’d bet we would all have been running around in nothing at all.

Are you sure it’s not 38 outside your apartment. That doesn’t seem right at all.

But don’t forget, the body creates it’s own heat. It’s not like putting a 98 degree bag of water in the room and seeing how long it takes to get to the ambient temp.

Right. The reason I put the “nitpick tags” around it is that my (intentionally silly) interpretation of the question isn’t very realistic. But given that, it’s still totally accurate. If the air in the hypothetical room has the magical property of immediately whisking away all radiated heat, then any solid hanging out in the room will reach air temperature as fast as the heat can travel to the outside surface. And heat can travel through a human body much faster than our metabolism can replace it. I’d wager that in such a magical room, if the temperature were 90 degrees, a person would be hypothermic within five minutes and unconscious within twenty. A 98-degree bag of water of similar proportions would be at a uniform 90 degrees within ten minutes.

Sorry to the OP for the continued hijack, but I think this does highlight a problem the question: the temperature is not the only variable. Also important is the conductivity of the air, which is affected by humidity and movement.

It’s that cold because I don’t use my heat unless it drops below freezing inside. As for “abnormal”, I’ll grant that my preferences are weird, but I doubt if I’m physiologically different from your average Joe. I can stand heat just fine; I get through the southern Virginia summers with no problem, I just prefer the cold. Seemed relevant to the thread, so I threw it out there.

The thermometer’s on my desk, which is most assuredly on the inside. It’s warmer now, but I’ll grab the other thermometer I own, put 'em side by side, and snap a pic of 'em tonight. (I do hope you’ll take the boxers part on faith.) You’re not the first person to tell me that this should’ve killed me – in meatspace, I try not bring it up for pretty much that very reason – but nonetheless, here I am.

I disagree. This is basically a room where the AC is set to very low temp. I’m quite sure that if I set the AC or Heat in my house to 90, I wouldn’t die of hypothermia in 5 minutes. What the OP is trying to say is that if the room is, say, 40 degrees, that all the running around you do isn’t going to warm it up anymore, it will remain at 40 degrees (just like if a AC kicked on). I think you’re reading to far into the question.

I’ll take it on faith that you don’t mind it that cold, I’d be more worried about electronics working properly, pipes freezing, and especially my fridge working as a lot of fridge compressors shut down if the temp get’s below 40.

Is that really true? I do know the body can get used to a lot of things… And I’ve always wondered how/why homo sapiens kept venturing out into coldass climates. But wow, that’s really fn cold to be out naked. Although I’m sure direct sunlight helps out a lot.

Right now I’m lying on a electrically heated bed. It puts out 250W on max. With this thing I can let the ambient in my room get down pretty low. I’ll try going 40, but haven’t done that yet.

Say the body needs 250W to survive at that temp. (Of course the electric heating pad is rather inefficient with the heat it radiates, and probably my body isn’t used to cutting off blood to all my skin, so let’s take this as an upper estimate.) 250 joules is 60 calories. 60 calories times 3600 seconds is 216 kilocalories per hour. I’d say that’s not improbably high. (Maybe 100W/hr is more realistic, but that’s still pretty toasty.)

The body burns a huge amount of energy in a day, enough to generate a generous amount of heat. The trick is sleeping, of course, but who’s to say the body can’t adjust to an always-high metabolism even in sleep.

The (admittedly inaccurate) thermometer next to me doesn’t want to dip below 50 although outside I know it is 24. I have my bed now set to third power. 80W with the majority of heat not actually going into my body. I feel pretty good, not even uncomfortable. But it’s hard to type fast and I feel slightly on edge. Overall, this is dumb. If God wanted us to live in these temperatures, he would’ve made us cute and furry.