Can humans hibernate?

I.e., “pass the winter in a dormant or torpid state”?

Because I’m sure feeling torpid. And I know that a lot of my fellow humans in similar climes have joined me in gobbling up carbs (the better to add a few pounds, hmm?) and feeling drowsier than, say, in the spring.

Could say I’m getting old, but I’ve felt like this in November for–years. I will start my nap the day after Thanksgiving and wake up in March. Oh, wait–that would probably mean I’d lose my job.

(Would the ADA cover it? Is hibernation a disability?)

True hibernation is a rather specific physiological state in which a mammal or other hometherm allows its body tempertures to drop to quite low temperatures - sometimes even close to freezing. Humans are incapable of true hibernation - it’s much more than just sleeping a lot during the winter. Even bears do not undergo true hibernation, only winter dormancy.

People can’t hibernate, they’re just to big. The maximum size for a hibernating mammal is around 5kg. Anything much larger than that won’t be able to store enough energy to bring it body temperature back to normal operating conditions without bursting into flame.

The problem is that hibernation requires the body temperature to drop way below normal. Like 20oC or more below normal. That’s great so long as you can keep it there, but at some point you need to wake up and start operating again. To do that you need to generate enough heat to get back to something approaching normal by burning fat. If you do that slowly then you lose a lot of the heat you produce to the environment as it’s being generated. That means that you need even more fat reserves. For a small mammal that’s not such massive concern because they don’t have much body mass to heat so relatively the heat loss in the warming process is small. They also don’t need to heat themselves too slowly because the heat being generated diffuses fairly rapidly around such a small frame. With larger animals it’s more problematic. Heat generated at one point doesn’t diffuse to other distant areas very well and the smaller the relative heat difference the slower it is and the more heat is lost to the environment in the slow heating process. As heat loss increases they run the real risk of not having enough fat to reheat themselves before they die.
But if they attempt to heat themselves rapidly to avoid the prolonged heat loss the areas generating the heat will need to get so warm they start to cook. For an animals the size of a cow I’ve seen figures that suggest they would literally need to reach temperatures where they would spontaneously combust.

It’s like trying to boil a 1000 gallons of water using a candle 1000 feet long. If you could break the candle up and burn it all at once you could boil the water, but you could keep the candle wick burning normally under the water until it burned away to nothing and the water would never boil because you’re losing heat faster than a slow burn can generate it.

So hibernation just isn’t an option for medium and large mammals. The larger hibernating animals like groundhogs and marmots will utilise the sun to a large degree in warming up so they don’t need as much energy in reserve to come back, but for them it may take several days to emerge fully from torpor and they often starve to death in that period. IIRC something like 1 in 5 of these animals that survive winter die in the period between emerging from their burrows and their core temperature reaching normal again. Animals at this size are really pushing the feasible limits of hibernation.

Now I know you’re thinking “bears” but bears aren’t true hibernators. Their body temperature only drops about 10oC below normal. Considering that human temperature will drop 3oC on a cold night you can see that it’s a relatively small drop. Bears that are said to be hibernating are really just sleeping. They frequently wake up and wander around, something which no true hibernating animal can do. For real hibernators it’s a one shot trick and if they wake up too early they almost always die.

This is a lovely analogy. I’m sorry there isn’t an icon of a little man tipping his hat. xo C.

Blake, you said that hmans can drop 3 degrees C on a cold night. This strikes me as absurd. Can you provide a cite?

::sigh:: humans

Actually, I noticed a pattern in my eating habbit, but it’s rather the contrary. I take up weight (15 pounds or so) during summer and autumn, so I’m now roughly at my maximum weight. Then, I tend to eat significantly less during winter and at the beginning of spring, I’ve reverted to my minimal weight. And so on…
On the other hand I indeed sleep more during winter.

I’m sure someone will have some cite about seasonal eating/sleeping patterns. I too would be interested.

Joe, I can’t provide a cite ATM. The text that came form has long since vanished. The process is known as insulative hypothermia. It’s well described in the literature for a range of animals including humans and occurs where people are exposed to cold conditions without adequate insulation. It results in a situation where both skin and core temperature fall well below the standard 37oC to minimise differences with the environment. It appears to have no health consequences. Unfortunately a Google search doesn’t return any specific figures on how low the core temp falls and although PubMed probably does I don’t have a subscription to full text ATM.
You can either take my word for it or try searching a college library or appropriate journals for information on insulative hypothermia.

I’ve no ref either, but a 3°C fluctuation under those conditions isn’t hard to believe, when the normal daily fluctuation in body temp is about a degree and a half:

here

Blake, absurd was not what I should have said. Sorry, poor choice of words. I’ll try and find something on insulative hypothermia.