Can You Hibernate a Human?

Hey, please take a second and leave us a review on Apple Podcasts, Spotify, or wherever you listen to the podcast. Thanks a lot. Hey, welcome to Science Stuff, a production of iHeartRadio. I'm hort Jam and today we're answering the question can we hibernate humans? We know bears can do it, some birds can do it, and even lemurs can do it. But could we get a person to hibernate? And would it lead to breakthroughs in emergency medicine, cancer research, and

So, my name's Kelly Drew. I am a professor at the University of Alaska, Fairbanks, and I direct a NIH funded center called the Transformative Research and Metabolism. So I've studied hibernation for about thirty years, so I'm very much focused on the brain and hibernation.

Incredible. I think you're the perfect person for us to talk to you today.

Awesome.

Maybe start us off, how do you define hibernation? What is it?

Well, the big picture of hibernation is that it's a metabolic adaptation where it suppresses metabolism and body temperature because sometimes they need to conserve that energy if food is not available, and many animals do it. Everything from some primates. There's the fat tailed lemur from Madagascar. There's marmots. Bears hibernate, not polar bears. Polar bears don't hibernate because they have food year round because they fish off the ice, but

Hummingbirds.

Yeah, there's a lot of different species.

Yes, hummingbirds hibernate too. Okay. The big question I had for doctor Drew was how is hibernation different from sleep?

Actually is thought to be an extension of sleep, So at least with hibernation, animals have to sleep to enter hibernation. And what I think is that there's a process that kind of flips a switch that allows the temperature to continue to cool, and then cold by itself plays a role in suppressing metabolism.

So hibernation is not just sleep. Something else kicks in in animals during hibernation, and that causes two things to happen. One through metabolism, meaning how active the cells in their body are slows down. And two, their body temperature drops. And this is a key feature of hibernation because normally your body doesn't let your body temperature go down. Even when you sleep, your body doesn't drop below one or two degrees of its normal temperature. It's all part of our survival mechanism.

We all have a point where if we get to a certain temperature, our bodies kick in the keaters, humans will shiver, we start generating heat. And so the trick is that during hibernation, your body allows it to get a little bit colder than what we normally do. So it's often thought of as well, you just lower the thermostat, reset the set point on the thermostat, and you get down to a colder temperature, and that temperature helps to

I see. So once we go into tibernation, our set point is set lower, and so the body gets colder and that doesn't do any harm to the organism.

Well, the ground squirrel is especially adapted to cold tissue temperature. For humans, if our bodies go below about thirty degrees celsius, then we can have cardiac arrhythmias, so the heart doesn't function all that well. But the ground squirrels are specially adapted and their body temperature goes down actually to minus three degrees below freezing, wow, minus three celsius, and they have no trouble with that.

So Hibernation isn't just about slowing your heart rate or going to sleep for a long time. Something really fundamental happens to animals that hibernate. Their entire bodies recalibrate to work at a lower temperature, which is something that normally our bodies very strongly rejects. I mean, if you go below thirty degrees celsius or eighty six degrees fahrenheit, as

And so the ground squirrels have adapted these temperature mechanisms so they keep things functioning even in the cold. I mean the same thing in your car. You know, you change the weight of your oil for winter compared to summer, so you want a little bit less viscous oil in the winter.

I see, I live in California and I'm from Panama, so this is need to me, that's the in fact that you need to change your oil. But in Alaska, I imagine that's a common thing.

Very common. Yes, So all those kinds of things. Animals have adaptations that allow them to tolerate different temperatures, and we don't know really what all those are.

Okay, here I had a lot of questions for doctor Drew, like what's happening in the brain of these animals when they hibernate, Do they dream or are they conscious? What triggers this hibernation mechanism? And then what's going on in the brain while animals are in the state.

Well, like I said, they are first sleeping, but as they cool, the magnitude of the brain waves they shrink and get lower and lower as the animal cools, until finally it becomes flat. And that actually looks somewhat like being in a coma, but they're not in a coma because they can be induced to arouse just by handling.

But it's more extreme than sleeping for example.

Right, Yeah, it's a different state of consciousness. So cold really continues to dampen the brain waves so that then they will become flat.

Meaning like the brain doesn't work at those lower temperatures.

You don't see any electrical activity.

That means, so basically the brain of the animal stops working. It's almost being brain dead, but not quite. In fact, it's something very different. Amazingly hibernating animals have been shown to be able to learn while they hibernate.

And they can learn actually when they're in this state.

Wow, what do you mean they learn? How can they learn if they're passed out?

What they learn is they habituate to handling. If you're like needing to do something with the animal when they're in hibernation, you can just handle them, and at first they'll be bothered by it, and they'll start to wake up. And if you do that over and over, they pretty much get used to it to where they just don't bother anymore. They're used to it. If you go in and handle them, they won't arouse. Wow, And so we consider that to be learning. It's called habituation.

Oh wow, that's uds like my teenage son when you're trying to.

That's exactly it.

Yeah, even though their brain activity is totally flat and they seem like they're in a coma or brain dead, the hibernating animal can still somehow process what is happening to it. It's really a very different state of being. Okay. The next question I had was what triggers hibernation.

We've got animals that hibernate according to season. We call them obligate hibernators. So they have a clock in their bodies that tell them what time of year it is, and no matter whether it's cold or dark, or whether they have food or don't have food, they will hibernate. And those are the ground squirrels and other species like the hamsters are what are called facultative hibernators, and for those, the hibernation has to be induced by short days, so

Oh, I see, let's just wait it out and see what happens. Yeah, what about like bears.

And bears are a little bit more facultative because if it's warm, they won't hibernate. If they have a whole lot of food, they don't hibernate. So bears, because they're so big, they don't actually get that cold. They don't get colder than about thirty degrees see, but they suppress their metabolism down to twenty five percent of basil metabolic rate. So basil metabolic rate is as low as you can go.

If you go lower, you're dead.

Kind of, yeah, you're dead.

Would you say? That's kind of a definition of hibernation is let you basically slow your body down to where you would normally be.

Dead, exactly right. And lots of people like to think of it as near death, and that way is very similar, and we like to imagine that hibernation is a state that kind of is near death, but it can be reversed.

All right, When we come back, we're going to talk about another interesting fact site to sit found about hibernation, and then we're going to talk about whether we could ever make it happen in humans. Don't go anywhere, we'll be right back. Hey, welcome back. We're talking about hibernation and whether we could ever do it in humans. And so far we've learned what hibernation is, which animals do it, what triggers it, and whether animals dream while they hibernate.

And for whatever reason we don't understand animals when they go colder than thirty degree c they have to rewarm every so often. Hamsters will rewarm every three to four five days. Ground squirrels rewarm every two to three weeks, and we call these interbout arousals. And during that interbout arousal, they sleep, so the flat eeg turns into slow wave sleep. They make glucose, they urinate just a little bit, they fluff up their nest, and they sleep and then they re enter torpurth.

Torpor, by the way, is what scientists call that deep low metabolism, cold temperature, almost brain dead state animals enter during hibernation. But what doctor Drew is saying is that animals are not in that state the whole time. They kind of stir and kickstart their body every so often throughout the hibernation period, and scientists think animals do this to kind of do body maintenance.

Something initiates that in about arousal. That evidence suggests that it's either an accumulation of something a waste that they have to get rid of, or a lack of metabolite that they need, like for example, glucose and so they need to make glucose and they can't do it when they're cold. So during hibernation, they may need to warm

So you're saying built into hibernation is this sort of periodic arousal where they do a little bit of maintenance and then they go back to hibernation.

That's right, that's right.

All right, And now we get to the topic of making humans hibernate. And the first question you might have is why hibernate a human? Well, according to doctor Drew, there are many reasons why we would want to put humans in a deep state of torpor. Okay, why would we want to hibernate humans?

Well, the most lowest hanging fruit is for critical care, particularly for brain injury. Like if you have a cardiac arrest that means like sudden heart failure, you fall on the ground and now you're comatose and you get resuscitated by CPR. Those people actually wouldn't know it, but they ultimately die from brain injury. So even though they can bring them back, the brain doesn't tolerate that lack of

How would that help them, Well, it may.

Just simply prevent the injury caused by the lack of blood flow, or it could stabilize the injury while every other processes kind of come back to normal and then allows the body to kind of deal with it at a slower pace at a better time.

Meaning you just want to slow everything down so that the injuries don't get worse.

Yes, right, having them enter this hibernation natural cooling state is expected to be more beneficial.

I see. So that's one reason we might want to hibernate a person in an emergency. Going into hibernation could cool the body down going into hypothermia, and that would slow the response to the body so that doctors have more time to deal with the injury. And this could be useful not just in heart attacks and strokes, but in any kind of injury where medical care is not easy to get.

So you could stabilize somebody by putting them into a hibernation state, and how you can get them to medical facilities. It certainly battlefield operations. Same with remote emergency care. If somebody falls mountain climbing or whatever and is injured but they can't be evacuated for a period of time, they could be stabilized by putting them into these states.

And another interesting reason to hibernate people is to maybe save the planet, he said, saving the planet. What's the scenario there?

So the other kind of grandiose ideas I've heard. One was, well, we can save the planet if you know, we can just all chill on a regular basis. We don't drive as much, we don't use as much electricity, all these things.

Like we would all go into hibernation every once in a while or every night or what do you mean?

Yeah, maybe for you know, like life holidays, Yeah, a couple of weeks at a time. I think it was inspired by COVID a little bit, because as horrible as it was, we definitely saved some things. You know, traffic was less and pollution lowered, wasn't so bad. People get pretty engaged in the life and hard to say, well, I'm just going to cut out for a couple of weeks or a month.

Yes, we could take hibernation vacations. Say you just want to check out for a few days or a few months, you could hibernate, and overall we would reduce human activity, which could be good for the planet. I mean, how many of us would like to take a break right now and not wake up until the next presidential election. And doctor Drew says taking hibernation vacations wouldn't just reduce your carbon footprint, it could actually help you dage and live longer.

But what's interesting and hybridating animals is they do live longer. Hibernation prolongs life, but you just kind of a pause. It's not the wear and tear on the body. You're really taking a break and cooling and rewarming. There's evidence that it has some regenerative properties, so you can actually you know, regenerate synapses, potentially regenerate muscle. But certainly in hibernation is interesting because even though they don't eat or

So they live longer, not just because they pause their body. But because there's other benefits to hibernation.

There could be that's still a hypothesis, but we're seeing evidence of cold and rewarming. The combination of cooling and rewarming stimulates regenerative processes.

I see. You would think that it's just your body kind of goes downhill when you're hybrided. But now there's something stimulating about hibernation. Yeah, fascinating.

But you know it's also a wonderful weight loss program.

What do you mean, what do you mean.

Well, you don't eat, metabolism is down These ground squirrels can double their body weight pre hibernation and then they lose all of that by spring, but they're fit and trim when they wake up.

Oh wow, that does sound like a really good program. Well I am all in on that startup. Right, that's Fitness Life Extension. Where do I sign a check for that investment?

Exactly?

That's right. You could use hibernation to lose weight during hibernation and the most burnt fat to stay alive. And so you could imagine going into hibernation for a while and waking up thinner without having to diet or exercise. Okay, the last super interesting reason to hibernate people is for space travel. You've all seen the science fiction movies where astronauts climb to a sleeppond and going to suspended animation. But why is that? How does hibernation help with goin

It's my pleasure. I'm very curious a lot your questions and to explore with you together, you know, the new perspectives of potential hibernating humans.

One day, can you please tell us who you are and what you do.

I'm a physician by training during research and mostly about organ protection, which has brought me to this field of spaceflight and how the organisms reacting to extreme environments.

Okay, now, according to doctor Chuk, there are several reasons why being able to hibernate would help humans travel through space. Now, you probably think the main reason is the one you see in movies, which is that space is huge and it takes a long time to get anywhere. For example, the near start to us Proximus centory is forty trillion miles away and getting there could take hundreds or even thousands of years. So being able to climb to a pod and somehow good sleep and stop aging means you

Yeah, we did a study with the European Space Agency. We designed the mission of six people going to Mars and back just theoretical design. What do would that mean? How much resources do we need? How much oxygen, how much water supply, food supply, so on. What would be the scenarios of being under hibernation condition versus another high condish And of course oxygen you save a lot, but

Only Doctors huqu In the European Space Agency calculated that for a six percent mission to Mars, where everyone stays awake the whole time, you need to bring about six tons of food, which is six thousand kilograms or about thirteen thousand pounds of food. And that's because the whole trip would take about two years, and so you need over two thousand, two hundred meals for six adults, and there are no grocery stores along the way, so you

Wow, exactly. This makes the difference. And when you just think about the implementation of a travel to Mars, you just need less payloads. Yeah, so this is why agencies maybe like it. Yeah, yes, we reduce the payloads. You need less stuff to get uploaded, and every kilochrome every pound costs a lot of money.

So hibernation would make space travel cheaper. Another reason hibernation would help going to space is that hibernation apparently makes you more immune to radiation damage. Space is full of harmful radiation, some of which comes from the Sun and some of which comes from cosmic rays, but it's a real problem for astronauts. It means that your chances of getting cancer out in space are much higher than if

When you relief of vicinity and go the younger fun old belt and having less protection, you will see more radiation effects there it will increase, and depending on solar eruptions, this may even be detrimental. So radiation resistance is a big thing.

Doctor Chuke says that scientists in Germany and Italy have done experiments where they induce torpor in test animals and they found that it kind of protects them from radiation damage. And the reason for that is not quite clear to scientists. Some think it's because your cells are not multiplying as much, so there's few chances for the radiation to cause inmutation. But it could also be because during hibernation, the body

When you stay lower in space, the problems may really kick off. It might be either the conditioning of the body so you're not experiencing gravity, pull on your bone, on your muscle, so you get rid of some volume that you don't need. The bones are gone muscles. Yeah, there was a research paper summarizes you need a new skeleton in the closet when you leave this even when you survive. But because your bones get really weak because of this deconditioning effect that you don't challenge your body.

I hadn't thought about that. So we've seen that in animals. Animals don't lose bone or muscle.

Exactly, they don't lose bone and muscle and wake up and up back to the business.

So to say, clearly, being able to hibernate humans would be a game changer for space travel. You could imagine hopping on a spaceship going into hibernation, and when you wake up, you're in Mars, and not only are you well rested and less damaged by radiation, but you feel great, maybe even in better shape than when you went to sleep. So now the question is can we actually do it in humans? Is it actually possible to hibernate people? When we come back, we'll ask our two experts this question.

So it takes about two years to go back and forth, which means you are isolated and confined for this period of time together with your colleagues in a small habitat. So they are adding a lot of psychological factors to it. There's even a syndrome called the Earth out of side syndromes. When it's just anticipating, you see the Earth going p sized. When you are landing on Mars. You can just see it, but it's very far away and you may imagine and not long it will take to be rescued or there's

What Doctor should Care is saying is that going to space is stressful. You're always in mortal danger, far far away from any help, and on top of that, you're stuck in a small space with other people and there could be drama if tensions get high. So being able to hibernate for most of that journey to Mars could really help everyone stay sane. Okay, and now we come to the big question, which is can we make hibernation work in humans? Well, according to doctor Kelly Drew, there

Well, there is a lab that is funded by NASA at the University of Pittsburgh and run by clinician named Cliff Collaway, and they are working in people. They're using currently known drugs anesthetics that are good at turning down the thermostat. He's using an anesthetic called dex metatomidine, and he sees that it is the best of all the

So a dentistine is a super important molecule that's used all over your body. It's involved in how we process energy. It's part of RNA and DNA, and it's a transmitter molecule in your brain. If you drink coffee or tea, caffeine wakes you up by blocking a dentisine in your neurons. And it also seems to be a part of hibernation. You can use it to trigger hibernation in animals or by blocking it you can delay an animal from hibernating.

And part of what we see is a little scary from a clinical perspective because there's very low blood flow, very low heart rate, but we are beginning to think that that is part of the metabolic suppression.

What do you mean, it's scary because it is so close to death.

It is so close to death, it really is. Yeah, So it has to be very well understood and very well monitored and you know known, because you know, we don't have all the adaptations that these ground squirrels have. We haven't already been optimized to tolerate the challenges of hibernation, and so we have to be very careful and understand it and know how to manage it so that it's you know, it's not risky.

So we have been experimenting with making this work in humans and there are signs that it could work. But the hard part is that we're still not sure how the whole body process of hibernation should get started, because in a way, it has to start from inside the body.

So hibernation it comes from your body. It's not external. Okay, it starts indulgeously. And this is what animals are doing. They have no drugs, nothing, They're just there and this is their mechanisms in start that we don't understand yet whether they start on the brain, whether they start on the cellar level, this is still open and under debate. Transferring this to the humans, I mean today we have no real real evidence that human is a hibernator, not

Now what's interesting is that there are examples of humans that can sort of go into hibernation. They're called yogis.

You know, the best examples are yogi's. Really well practiced yogis can do this. I mean they can lower metabolism, lower blood pressure. They do that mostly through their breath and involves a parasympathetic nervous system. And that is something also that we see in hibernation is they definitely use their parasympathetic nervous system as they enter hibernation. So that's another nice human example of what's possible.

I mean, yogis, this is real.

This is not oh, this is real. This is these are you know, life practicing yogis that can lower body temperature and metabolism, heart rate dramatically, not eat for days. I don't know what the record is. It's not in the literature as much as it's you know, just stories, but there's certainly some extreme ability. Also, you know, people who dive really you know, prolonged diving, breathholding can develop some of these skills.

Wow, it's under our control.

Kind of that is under our control with training.

Oh wow, fascinating. So that's where we are today. Can we hibernate humans? We're sort of at the point where we have a lot of knowledge about hibernation in some species of animals and we have to dream of making it work in humans for things like space travel. Now it's just a matter of closing that gap. We need to understand more how hibernation is triggered in animals, and we need to start testing out whether those strategies can work in people and whether our bodies can survive being

It's really ripe for discovery, and yet it's also kind of thinking outside the box and hard to get resources to do to study. So I appreciate your program. I appreciate being able to share some of the possibilities and I hope people are interested and will support it.

Yeah. Yeah, Like I said, I'm ready to invest.

This idea.

All right, we will have to talk, all right. We hope you enjoyed that. Thanks for joining us. I'm going to go take a nap now, but don't worry. I plan to wake up before next week's episode. See you. Then, you've been listening to Science Stuff production of iHeartRadio, written and produced by me or hitch Ham candidate by Rose Seguda, executive producer Jerry Rowland, an audio engineer and mixer Kasey Peckram,