"falling asleep in cold weather = death"? really?

I have read that people in cold survival conditions have tried to stay awake, fearful that if they fall asleep they won't wake up. I have read others say that if a human goes to sleep then gets too cold, they will wake up on their own.

Where is the line here? It seems like if you are not yet hypothermic, going to sleep shouldn't be feared. You almost certainly need the rest. Perhaps though if you are already too cold and past the point of effective shivering then you may well not wake up.

Anyone have authoritative info?

It seems to me that if you can keep your core temperature high enough, there wouldn't be a problem. But if you're constantly losing body heat, where's the line between making a rational decision to go to sleep, and just curling up in the snow and dying of hypothermia?


"... Saint Alphonsus Regional Medical Center has put on The Ski and Mountain Trauma Conference each year for the past five years.

"The conference, held recently at Sun Valley Resort, brought together 400 ski patrollers and medical personnel from Idaho and its surrounding states to learn about such widely differing subjects as assessing patients in the wilderness to avoiding complacency in swiftwater rescues."

From Nate Ostis, who heads up the McCall-based Wilderness Rescue International l (http://www.magicvalley.com/lifestyles/recreation/article_09c2b1d7-5142-5416-941b-ba5410d4fb23.html):

"True or false? In a survival situation, you may die from hypothermia in your sleep if you go to sleep when you’re cold.

"False. Unless you’re severely hypothermic, uncontrollable shivering will wake you up before you get too cold. When that happens, run around or do some jumping jacks or something else to warm up before trying to catch another nap.

"True or false? Dehydration and fatigue contributes to frostbite.

"True. Dehydration affects blood flow through capillaries. And fatigue clouds our judgment and decreases our vigilance."

Sue

Yeah, so the circumstances in which I've heard of people dieing when going to sleep in the cold (and I have no idea if they're entirely true stories) revolved around people who were already malnourished and cold, likely suffering from hypothermia. In other words you won't freeze to death on your first night because you fell asleep, but perhaps further on in an ordeal. No positive idea though.

It doesn't take cold weather to get hypothermia. There have been documented cases of people succumbing to the effect of hypothermia when the temps were in the high 60's to low 70's. This occurs quite often with adventure racers where after a few days of punishing conditions, extreme physical demands, lack of sleep and lack of proper nutrients / fluids, their bodies are unable to produce the energy required to maintain body temperature.

Back to the OP"s question. You just don't simply fall asleep and not wake up. Susan's post pretty well explains it and the hypothermia article on wikipedia also has some good general info.

The sources I have checked contain no dire warnings about falling asleep in cold conditions; my impression is that it is an old wives tale. If you are hypothermic and your condition is not corrected as your body temperature declines, you will lapse into unconsciousness, leading to death.

My own experience when I have tried to sleep with inadequate insulation for conditions, is that I will fall into a fitful sleep and then wake from the cold, sometimes shivering. On the worse such occasion, I melted snow, made a hot drink, and dropped off to sleep again, repeating the cycle through the night. I had notably more energy the next morning, despite sleeping very little.

The main thing is to recognize incipient hypothermia, take measures, and let sleep take care of itself.

Regarding metabolism helping to maintain body temperature...... Thinking hard and/or being emotional (anger, distraught, fright, sexually aroused. etc.)will generate metabolic heat by burning glucose. I have to admit I have not read this in scientific journals, but I am relaying what I have experienced repeatedly in life. (Well, anger, SA and thinking.....fright and distraught-less heat)

gimpy

As understand it it isn't a question of sleep or not to sleep. If you are hypothermic you need to be taking action to warm up or better protect yourself. Sleep in this case represents failing to act and allowing the process of hypothermia to continue to advance. The likely outcome would be grim.

Yes, hypothermia, especially coupled with dehydration (I'm always surprised how much warmer I feel if I'm well watered), hunger and fatigue, can cause you to feel like someone 'pulled the plug' and to feel strongly compelled to sleep. But it isn't the sleep that gets you. It is sleeping instead of actively correcting the situation.

Also, in my limited cold weather experience and understanding, if you went to sleep warm you are going to wake up long before hypothermia sets in. Of course this is greatly helped along if you are also well fed and watered, and not gravely fatigued.

I have talked to people who claim that in extreme cold, even outside hypothermia, that you better not sleep. As if the combination of sleep and cold was somehow toxic. Like the Sandman and Jack Frost get together and set about slitting throats.

Staying awake when not in actual danger of hypothermia sounds to me like a fine way to get into trouble by way of fatigue and sleep deprived confusion. Lots of survival situations went bad when people got so fatigued that they couldn't think straight and made some dead simple rookie mistake, or simply walked around in circles. Sleep is as vital to survival as food and water.

An interesting topic. How reliably do hypothermic people recognize that they are hypothermic? Since hypothermia starts affecting your cognitive abilities, I think it would be quite easy for a severely hypothermic person to "forget" the fact that they're hypothermic.

I once saw a show on Discovery Channel that described the final stage of hypothermia, which includes extreme sleepiness, before the person drifts off and dies. Maybe that's the scenario that people are trying to put off?

I have read or watched TV about quite a few cases of survival from all kinds of dangers like trauma, disease, starvation, etc., where people instinctually told themselves to stay awake and concentrate even though their body was telling them to just give up and go to sleep. Arguably, these survivors should have succumbed, but somehow they survived. Was it willpower? Could be.

Fascinating thread, like a Mythbusters. I have no empirical evidence or personal observation to add. In fact the only real life example I can recall is Beck Weathers when he fell asleep on Mt. Everett during the 1996 tragedy. I suppose if you don't know the story you could google his name or better yet read the book "Into Thin Air" then his autobio

i would assume that the "don't fall asleep" advice comes from the old days when hypothermia was not well understood.survivors would tell of others in the group who fell asleep and died not understanding that sleep was part of the hypothermia process.
my favorite "don't sleep" story is out of a old--1950's--TV program where the hero would not let a bottle of whisky be drunk up because when it froze he would know it was 40 below.i don't recall what was going to do then!!!???

The thing that prompted me to post this question is an episode of "I Shouldn't Be Alive" I saw recently, in which a solo peakbagger gets badly injured in an avalanche and spends about 3 days crawling/limping his way out. After at least 2 days of no sleep, exhaustion and blood loss, he struggles to stay awake thinking he will die if he succumbs to sleep. He falls asleep anyway and wakes up the next morning under a pile of fresh snow, feeling surprisingly refreshed.

The guy was super fit, which is always a great asset, but still he was wearing minimal clothing in subfreezing weather while tired & injured.

My experience precisely...You need your forty winks.

Slight thread hijack, I just recently watched Frontline's Storm Over Everest and found it excellently done. It includes interviews with the survivors and pictures from that day, and tells the story well.

If I remember correctly, Beck Weathers was left for dead and fell asleep. He woke up some time later with no pain, noting that his arm and other extremities were frozen. It was very peaceful, but then he thought of his family and forced himself to get up and walk until, amazingly, he found the camp. (Incidently he was then left for dead a second time.)

I've heard that people who get frostbite more easily are less likely to die of hypothermia because the body is quicker to cut off bloodflow to the extremities in order to preserve core temperature. But that's just something I read from who knows where...

Back on topic, my experience has been that I'll wake up if I get too cold. I once spent the night in an unheated cabin with temperatures dropping to 37 degrees, and I only had regular bedding, i.e. mattress, blanket, pillow. I figured out a multitude of tricks to keep warm that night. It seemed my shivering would wake me up each time I became too cold, I'd shift position and my shivering would warm up my cocoon sufficiently until I could sleep again, and then that cycle was repeated over and over again. Not fun, but not particularly dangerous either.

I'd be more concerned if I was cold enough that I went beyond and stopped shivering. Hopefully I'd have enough presence of mind to get up and move instead of sleeping.



That's what I've always thought.

We watched that too Glock. I was of the same mind - if he falls asleep, he's dead. It would have been like giving up. Not so much because of the cold, but because of his injuries. The snow no doubt insulated him but his will to live was probably the biggest factor in keeping him alive. That and he obviously needed his rest. It's a fine balance, I guess. I can't fathom how he possibly did what he did. I'm shocked that he made it. (Our family had a bit of a giggle about this forum, and a particular thread, when he crossed the streams.)

At the end, he said he went right back to the mountains again. I wonder if he keeps a psk in his pocket now, or wears better clothing when he's out there? I kept thinking, if only he had a lighter or a SAK or a....

Great point, that show was another lesson on "if you don't have it with you it can't save your life". He lost his pack and was fubared.

Recently I saw this issue come up yet again when reading a survivor's account of dealing with cold weather. So I took a chance and emailed the renowned Dr. Gordon Giesbrecht, asking him about his thoughts on "dying in your sleep from cold". I even sent him the link to this thread and asked if he would consider posting here. I can't think of a better expert to consult on this topic.

I highly recommend the 2nd edition of Hypothermia, Frostbite, and Other Cold Injuries which was revised by Dr. Giesbrecht.

Check out Dr. Giesbrecht's Cold Water Boot Camp, especially their videos.

If you are cold enough that you will die from hypothermia, how will staying awake, if you could do so, prevent death?

I vote for mostly a myth.

This mindset assumes that we don't have any control over our bodies.

How many stories have we heard, and I have seen examples of it myself, of people who are very old or terminally sick and who hold on just long enough to reach some major event (a wedding, a graduation, a birth, until the other spouse passes first, etc.) and then they quickly die afterward? Or conversely, how many spouses pass away shortly after the first spouse goes? Something in them just gives up. Or yogis or martial art masters and others who can control aspects of their bodily functions that we normally think are beyond our control.

Modern science is just beginning to understand the mind-body connection in a more systematic way.

Unfortunately, the more dangerous stages of hypothermia affect your cognitive ability and make you confused, so it's difficult to realize that you're hypothermic so it can be difficult to know whether it's OK to sleep or not. In fact, you apparently often feel hot during the final stage. Perfect for nap time.

I agree with this. If we take it as gospel that "if you're cold you can't trust your mind at all because you may be hypothermic and not thinking clearly", then you should never sleep at all in winter, since you may be hallucinating that you're in a warm, dry cabin by the fire...!

Who said anyone came down from Mt Sinai with the commandment "Thou shalt not sleep if you're cold..."?

Of course, if you can still think clearly, then you're not that far gone, no matter how cold you feel. Same thing if you're still shivering. But once you stop shivering or once you start noticing that you can't think clearly and have trouble concentrating, you've obviously entered a more serious stage.

I saw this TV show once where alpine mountain climbers swallowed temperature sensors. The data showed that the climbers core temperature stayed up as long as they kept moving, slow as that pace might be at extreme altitude. If they stopped, some climbers were able to maintain a tolerable core temp, but in others, their core temps immediately started heading down to dangerous levels until they started moving again.

So, when you're that close to the borderline, the ability to differentiate whether you can stop and rest or whether you are in danger of severe hypothermia is critical. But if you're already near that point of hypothermia, that's kind of like asking a person who's been drinking heavily to assess whether they are safe to drive. (A clear headed buddy is helpful in both the hypothermia and DUI scenarios!)

Actually, this physiologic difference observed in the TV show probably partly explains why some people in dire straits can fall asleep and survive, while others succumb to the elements if they drift off to sleep. People come to differeing conclusions based on such survival stories, but miss the possibility that the people were quite different in some crticial way.

Look, you're also going to be fighting other reasons for wanting to sleep--physical and mental fatigue, dehydration, malnutrition, lack of sleep, shock, injuries and/or blood loss, maybe side effects of your normal prescriptions or OTC meds, maybe side effects of a Vicodine you took for an injury--so it's not an easy thing to sort out whether you're sleepy from late stage hypothermia or other reasons and whether it's OK to sleep.

I can't tell from your post if you're 1) referring to the source of the original question, or 2) if you're referring to my response to some followup posts.

If it's 1), then that answer to your question is "the many, many accounts I've seen/read from survivors who say they were afraid to let themselves sleep, lest they die from cold".

If it's 2) the answer is: some of the posters above basically said that. Look at their posts. They advise not "believing" your own judgment about hypothermia because that judgment may be clouded by... hypothermia.

It's a chicken & egg argument. Myself and NightHiker are arguing against it.

My layman's understanding of hypothermia is that, barring something like immersion in ice water, it's not so much that your core temperature simply gets too cold, it's that your body runs out of fuel (blood sugar) to burn.

Or: You don't stop shivering when you go from mild to severe hypothermia, rather you go from mild to severe hypothermia because you've lost the ability to shiver.

I can't see how it matters if you're awake of asleep, unless there is some action you might take to improve your situation while you're awake.

I suppose one rule of thumb could be that find yourself shivering, you might want to get up and perform some useful work instead.

For indications of hypothermia, watch out for someone with the "umbles". As in Stumble....Mumble....Grumble...Fumble...

The insidious thing about hypothermia is that among the first of your functions to degrade is your ability to reason. That is probably one of the best reasons for being with a group, especially in challenging conditions.

Being hydrated, preferably with warm drinks (think nice cup of tea) is critical as well. It is surprisingly easy to become dehydrated in cold weather - you cannot depend upon thirst as an indicator.


I have bivouacked in very cold conditions when I was fairly exhausted, sleeping very fitfully through a long winter night. I was amazed at how much more energy I had the next morning, even after a lousy night's sleep.

I learned the same thing in EMS. I worked my day regular day job and worked on the ambulance at night. I found that even if I never really went to sleep, but just laid quietly in a dark room for a couple fitful hours of occasional dozing, I felt better the next day than if I kept on my feet all night. This was true even if "staying awake" was just watching TV, not running tough calls.

There was a definite, repeatable difference.

I got an email response today from Dr. Giesbrecht. He is willing to register here and post on this topic, but the registration process ran into the ditch and he is stuck. I am going to follow up with Blast for help; stand by.

Great summary, AKSAR. Thanks!!

I've woken up shivering ... probably in early stages of hypothermia. Happens if you forget your sleeping bag, and you are above the freezing level. Hahaha! Doesn't happen often though - you LEARN not to do that :-)

The stories where people are telling each other not to go to sleep usually are expeditions to high mountains and polar regions. In those conditions, the adventurers are already in a pretty serious situation - they already have serious hypothermia, they probably have some frostbite, they don't have any food (or heating supplies) left, and they may be low on oxygen. So these are not just people who are feeling cold - they have fading life signs. In that circumstance, I would think that you probably could fade out mentally and just be gone.

Pete2

A severely hypothermic victim will become unconscious as a result of significant brain cooling; this is not going to sleep and is an inevitable progression towards death. However, the idea that a cold, or mildly hypothermic victim will die because they go to sleep and as a result, just drift off into oblivion is not likely. Anyone who has tried to sleep when they are cold knows that it is very difficult to sleep as they shiver in agony. I general, if you are able to go to sleep (which is generally good for you as you need rest), you will wake up due to discomfort long before you actually become hypothermic. Bottom line, if you can sleep great! You will not miss all the warnings and defences, and wake up dead.
For further info check out our fee downloadable educational files at
www.beyondcoldwaterbootcamp.com
Gordon Giesbrecht, Ph.D. (a.k.a. Professor Popsicle)
University of Manitoba

Thanks for the info! Welcome to ETS!

thnx for piping in, doc!

Dr. Geisbrecht, I have been following your work for a number of years now. I believe you are having a profoundly positive effect on peoples understanding of hypothermia. Welcome, and thank you for joining this forum!

Welcome, Doctor. I'm an ice machine engineer by profession, so naturally I take great interest in your work!

Thanks a lot, it is great to stamp out that old myth by someone who knows what he talks about.

Wow, great to have the definitive source here at ETS! Welcome, Doctor!

thanks Doc. and stated in a way a guy like me can repeat to others.

Thanks for the input, doctor.

The logical follow-up question is whether keeping the severely hypothermic person awake (or concious, in this case) out in the field can forestall death for any significant length of time? Or is that basically out of anyone's influence at that point due to brain cooling?

Let us hope he will find this forum useful and won't give us the cold shoulder.....

Today I stumbled across Paul Kirtley's bushcraft blog and noticed another confirmation that one shouldn't worry about sleeping in cold weather. If your body gets cold you will wake up.



Here's another example where survivors needlessly forced themselves to stay awake for many days straight in the belief that if they went to sleep in the cold conditions, they wouldn't wake up. Their ordeal was made significantly more miserable by their mistaken thinking.

Thank you Glock-A-Roo for pulling this out of cold storage.

Dr. Giesbrecht gave some expert information and looking at his videos and documents it is worth the time to review it to know what to do both if you're hypothermic or caring for someone else who is.

This site has such great information. I thank you all for your time sharing your knowledge.

Survival Training is full of Myth's like "Don't Eat Snow" to "Don't Sleep in the Cold". I have often wondered at how bad our teaching was/could be without proper research. Modern Medical & Survival Research has changed may of our methods over the last 40 years if you look up the what and why, often advice has changed radically, once the laws of physics and physiology have been applied to the problem, instead of "Assumptions".

What is the myth?

As I know it; one should not eat snow because it is cold and therefore lowers your body core temperature when melting in your stomach. For an allready hypothermal person it makes hypothermia even worse.

But this is not a myth, it´s a sientific fact.
The heat that melts snow in stomach is drawn from the body.

In theory, yes.

In practice, not so much. Human physiology offers a direct defence against ingesting too much freezing material too quickly. It's commonly called "ice cream headache."

Normally, this suits me just fine (outside populated / popular recreation areas, of course -- I'm not fond of drinking dog poo or skiing wax). As long as I am moving about I usually have plenty of surplus heat which needs to be removed, one way or the other. Using a few calories of surplus body heat to add a bit of water in my tummy seems like a brilliant idea to me. But a mouthfull of snow doesn't have many grams of water, so this practice is just a fraction of my water consumption. And I stop eating snow when activity stops or if I start feeling cold.

On my last trip I re-learned old army tricks from my army officer friend:

• A water bottle has a wide mouth, making refilling with snow easier
  
• You start re-filling with snow immediately after your first sip, always stuffing it full (so it always contains water with snow in it, which will melt quicly, not "wet snow", which melts slowly)
  
• in sub-freezing temperatures you wear the water bottle on your body, under your outer layer of clothing

Now the water-bottle-on-your-body trick isn't really nescessary for your average day hike unless it is REALLY cold. A water bottle doesn't freeze for many, many hours if it's inside your backpack, among your extra clothes and whatnot. But the practice is sound, and something I'm happy to adapt for trips to remote areas.

Yes Snow is Colder that Tea or Hot Water, but the Calories lost are not relevant compared to how fast you will become "Combat Ineffective" from Dehydration. Inuit eat snow all the time as in there cold dry environment, they need water and the only form they have is snow.

I figure the "Don't Eat Snow" Myth came from individuals actually eating snow blocks and being told don't eat snow you will get chapped lips, which can be debilitating in the wilderness over the long-term. Then they were told to act like an Inuit and ball up a small ball of snow and suck on it. This way you cannot cool your core body temperature. Think 7/11 and Slurpee's, anyone ever die of Slurpee headache, no way, its gods way of telling you to slow down sucking on the snow lump/Slurpee. Yes Hot tea will be better and over time you will use more calories than a hot liquid, but you will become Dehydration far faster than you will lose calories.

What I think happened over time is we shortened the sentence and then over time forgot what was actually said and simply made assumptions. i have a nice case study of a guy who sucked on snow lumps for 43 days and lived to be rescued in the Himalayas. If I am thirsty and have no water I suck on a snow lump, dehydration will kill you way faster than a little low level calorie loss.

I've seen someone claim that your body would consume more water burning those calories required to melt snow than you'd recieve from same snow. This, I believe, is the source behind the revival of "don't eat snow"- myth.

I am sceptical. And stories about people surviving for days and weeks with no liquid water present, only snow, makes me think that this is bogus.