I’d like to skip the whole Christmas season.
Not yet.
But I sympathize.
As someone with bipolar I get periods where ill sleep 17 hours a day for a few weeks at a time. Lucky that doesn’t happen often because it wastes time/life and makes it hard to do stuff.
This is the closest to hibernating in humans I would imagine
Large animals don’t go into a true hibernation. They become lethargic and sleep. Body temp remains fairly normal. I would imagine if the right hormones were somehow induced a human would react similar to how a bear reacts.
Booze
Last I heard, what bears do is in fact true hibernation. Their core temperature doesn’t drop as much as smaller mammals, but that’s just due to the fact that, due to their size, they have a much lower surface to volume ratio.
If bears can do it, then it’s hard to see why other large mammals like humans can’t. But nobody’s figured out how to manage it, yet.
Can you remember where you heard that? Bears regularly wake up and take walk during their “hibernation” and can be roused by being touched, loud noises etc. None of that suggests true hibernation even without the temperature issue.
I don’t see how that makes any difference. A low surface area might make the temperature of a larger hibernating animal fall more slowly, but it doesn’t explain why it doesn’t get just as low after several days.
A hibernating bear lowers its body temperature less than some humans do during a normal night’s sleep. If bears are hibernating, then so are humans.
To hibernate you need to decrease you energy demands, which means dropping your body temperature to a few degrees above freezing. If you don’t do that, you will need to become morbidly obese to avoid starving to death after a few weeks.
But if a large animal lowers it body temperature to that level, it will never be able to raise it again. The energy required to raise the temperature of 100 litres of water from 4oC to 40oC is huge. If you try putting that energy in slowly over a period of days, enough will all dissipate that you will never be able to carry enough fat to warm up. If you try putting it in fast enough to bring the temperature up, the temperature of the heating elements will need to be high enough to cook flesh.
A small animal can get away with hibernation because the heat only has to dissipate a few inches from the heating element to any other part of the body, so a slow steady heat of 40oC will rapidly raise the whole body to that temperature. But if you place a heating element at 45oC next to a slab of beef at 40C, it will take days to bring the whole slab up to temperature. If you turn the heating element up to 80oC you can raise the temperature faster, but it will cook the meat.
Even animals of a few kilograms, like marmots, have problems with hibernation because they are too large to warm themselves up. Marmots are reliant on heat from the sun to provide the energy needed to bring themselves out of hibernation. If the sun doesn’t shine when they wake up and they can’t return to hibernation, they can easily starve to death.
Even a hibernating animal has some metabolic processes continuing in its body, generating a small amount of heat internally. The more volume you have, the more heat you generate in this way. That heat is then dissipated through your surface, at a rate proportional to your surface area and to the temperature difference. So there’s some equilibrium temperature at which the heat lost to the environment will equal the heat generated internally. That equilibrium temperature will always be greater than the temperature of the environment, and the larger the body, the higher it will be above that temperature. For an extreme example, the Sun has a lower heat-generation density than the compost pile in your garden, and yet due to its enormous size its equilibrium temperature is at thousands of degrees.
Plus, as you say, the energy required to change the temperature of a large amount of water is huge, and that goes both ways. Just as it takes a very long time to warm up the mass of a bear, so too it takes a very long time to cool it off.
It appears that it’s fairly recent that most scientists agreed that what bears do is hibernation.
That seems to be assuming that the so-called “heating elements” of the body are concentrated in some limited portion of the body (like the red-hot coils in my wall heater that are attempting to heat up the entire room), and will thus cook the nearby flesh while trying to heat the rest.
Aren’t the “heating elements” of the body rather finely distributed throughout the body? Aren’t they the [del]midi-chlorians[/del] mitochondria, which are in every cell? If the body simply cranks up the voltage to the mitochondria, why can’t they turn out enough heat to warm up just the host cell, with out cooking that cell? It shouldn’t be necessary to blast out enough fire to heat adjacent cells, which have their own mitochondria for the purpose? (Is there a problem with providing every cell with the fuel needed to do this?)
Am I totally off-the-wall here?
I read that bears are able to prevent uremic poisoning (from the waste products in the urine and blood), by periodically waking up to take a pee-how do the avoid dehydration during those long naps during hibernation?
If “coldsleep” (needed for humans to travel to the stars), we need to understand this.
Some simple sanity points on heat and temperature.
As a limiting case for any animal - how long does it take for its body temperature to drop to ambient when it is dead? It isn’t all that long.
How long will it take to heat up, and how much energy? Even without bothering to do some simple maths, it can’t be more energy than the body lost when cooling down from when first dead, and the needed reserve energy supply no worse than the energy that would have been used had the animal been alive (and expending energy to stay warm) for the same period of time as it was cooling down.
I suspect a critical problem with body core temperature is that metabolic processes are keenly linked to temperature, and if you want to really drop the rates, you will need to get the temperature down. If you don’t, the basic rate of energy burn will probably not come down enough.
That is a good question, I know bears will use up a very large portion of their fat durring hibernation as they maintain their body temps near normal, as they burn fat I would guess that the fat contains water which is reabsorbed into the cells.
I know quite a few guys who cook off bear fat for the grease, they would have a good idea how much water is in bear fat.
Another issue is pressure sores from not changing position. I don’t know how bears get around this. I suspect they change positions or the fatty portions on the surface distribute the load more effectively than humans do.
Bears don’t just wake up and pee periodically. They actually break down urea while they are sleeping and recycle it, at a cost of using up some of their fat reserves. Instead of peeing it out, they use it to rebuild muscle and other tissues. Since the water isn’t excreted, they don’t dehydrate.
ETA: Ninja’d, but anyway:
Actually all hibernating animals, even obligate hibernators periodically wake (or at least enter a state where their body temperature returns to a normal range and they are responsive to outside stimuli). One theory is that it is necessary to periodically activate the immune system.
Hibernation is not defined by body temperature but by rate of metabolic processes.
“The American black bear undergoes a 3-5 month winter hibernation during which time bears do not eat, drink, defecate, or urinate. During hibernation renal function (GFR) is 16-50% of normal but urine is reabsorbed across the urinary bladder (UB) urothelium thus enabling metabolic recycling of all urinary constituents.”
From The urothelium of a hibernator: the American black bear. Link