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