Why can't humans be made to hibernate?

[bryanl]

For the purposes of spaceflight and reducing living expenses, of course.

Also bears don't lose calcium during hibernation, another problem humans have with weightlessness.

 

[wuliheron]

As mammals go bears are pretty low on the intelligence scale and have a low brain mass to body mass ratio. You might as well ask why whales or elephants don't hibernate. The simple fact is their brains are much larger and require a great deal more oxygen and nutrition then a bear's. If you look at even simpler animals a "bear mite" can be completely frozen for millions of years and still come back to life and reproduce.

Among other things bears can tolerate large amounts of vitamin A stored in their livers. Enough that if a human ate their liver they would turn bright orange and die. Birds can eat cyanide, cows can eat grass, but humans can't eat that much vitamin A, cyanide, or grass without dying. Bears spent millions of years evolving the ability to hibernate and it looks like any solution that might allow humans to do so will be at least as complex and quite possibly not nearly as effective.

 

[dkozloski]

A drug induced coma is as close as you can presently get.

 

[gaidensensei]

Surface area to volume is a good thought for physical limitations.

Circadian rhythm concept fits broadly, as the body seeks to regulate itself.
The complex answer likely has to relate with cellular respiration and hormonal activity and functions.

For one, cortisol releases into the system at the peak of the day during a normal sleep schedule, providing an increase to blood glucose and metabolism, generally making people hungry during the day. Hibernating animals get a decrease into cortisol production during wintertime, thus allowing them to sleep effectively for long periods of time. [a]

[a] source: http://www.ncbi.nlm.nih.gov/pubmed/2842983

 

[pm]

There have been experiments in animals with hydrogen sulfide induced hypothermia that have had mixed results.

Mark Roth delivered a TED 2010 talk on using H2S induced hypothermia in animals and injected NaS to reduced metabolic rates in humans - they are in phase II trials right now.
text interview:
http://www.wired.com/epicenter/2010/02/mark-roth-on-mice-and-men/
video/audio:
http://www.ted.com/talks/mark_roth_suspended_animation.html

 

[TecHNooB]

apparently bears wake up a lot during hibernation. it's not as continuous as we once believed.

 

[LucJoe]

There have been experiments in animals with hydrogen sulfide induced hypothermia that have had mixed results.

Mark Roth delivered a TED 2010 talk on using H2S induced hypothermia in animals and injected NaS to reduced metabolic rates in humans - they are in phase II trials right now.
text interview:
http://www.wired.com/epicenter/2010/02/mark-roth-on-mice-and-men/
video/audio:
http://www.ted.com/talks/mark_roth_suspended_animation.html

From the wired interview:

But then you have these freaks of nature. . . . There’s a retrospective study that was published in the New England Journal of Medicine ten years ago that shows that 50 percent of people who have been without a heartbeat for three hours [in cold conditions], and are re-warmed appropriately, survive without neurological problems. The people in that study spent at least three hours below 28 degrees. The record is a 29-year-old skier in Norway who went for nine hours. Her core temperature fell to below 14 degrees C. Remember, people are large bags of water; they take a long time to cool off and a long time to re-warm. It took her nine hours to get to a point where they could re-start her heart, and she went on to be the head radiologist in the hospital that treated her.

What?

So she spent 3 hours dead in the icy water then another 9 hours being "re-warmed" THEN i assume they paddle her heart and she wakes up?

I was under the impression any more than 10 minutes after your heart stops causes serious irreversible brain damage.

 

[firewolfsm]

That's if the brain is still active, in which case it would very quickly exhaust all fuels and function erratically until death.

If the brain is shut down, if the cold deactivates it before the heart stops beating, then maybe.

 

[jackofalltrades]

I am a EMT and I saw a person in a diabetic coma who laid for over 10 minutes I was there with no perceptable heartbeat hooked up to a heart monitor and no breath for the same time we administered glucose in a gel under the tounge and less than 2 minutes later this supposed Dead person was asking what all the fuss was about!

If you could hold someone in state like that, maybe while cooling the body somewhat; who knows how long the person could be kept that way!

 

[KillerCharlie]

I wish I was a bear. You get to sleep during the crappy seasons and only have to be out in the summer. And you're a bear so other animals don't screw with you.

 

[wuliheron]

It think the record for a human being is about half an hour without oxygen. Not exactly what I'd call hibernation.

 

[silverpig]

apparently bears wake up a lot during hibernation. it's not as continuous as we once believed.

I heard they don't actually hibernate. They just sleep a lot and hang out in their dens. Kind of like all those WoW kiddies.

 

[dave_the_nerd]

I wish I was a bear. You get to sleep during the crappy seasons and only have to be out in the summer. And you're a bear so other animals don't screw with you.

Except for the humans... :sneaky:

 

[Puppies04]

It think the record for a human being is about half an hour without oxygen. Not exactly what I'd call hibernation.

1 hour 19 minutes and im sure i read somewhere there have beeen cases of children being resuscitated 3-4 hours after drowning.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC286328/

 

[Puppies04]

Oh and i definatly remember hearing on QI (telivision program for anyone who hasnt seen it) that there is a town in europe somewhere where the people all used to gather in a single hut and go into a kind of hibernation, apparently they got up every week or so to urinate and drank a small amout of water then laid back down again. Sorry can't find a link but that TV show does a LOT of backgroud checks before they quote something as fact