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!!!???