Putting humans in a hibernation state

to make interplanetary journeys has been a staple

of science fiction films like Aliens, and Passengers.

But some people think it might one day become a reality,

and even a solution to get people to Mars.

The only problem?

Humans don't hibernate.

But bears do in ways that we might one day emulate.

It's not unique to one particular class of mammals.

And I think as long as those pieces are there in humans,

then we could translate that into situation

where hibernation could be induced.

That's Heiko Jansen.

He studies hibernation in bears.

We talked to him about what human hibernation might

be like and the ways it could help us hurtle

through space or cure our illnesses.

So, tell us a little bit about

what's interesting physiologically

about bears and hibernation.

Wow, where to start. [laughs]

Everything.

No, it's really quite an amazing physiological state

where the bears can survive for months

without eating or drinking.

Their body temperature,

when they're hibernating, doesn't go that low.

It only drops to about 30 to 34 degrees centigrade

versus 37, but if you compared that to a ground squirrel,

they may drop their temperature to 0,

or sometimes even below zero.

They still reduce their metabolic rate,

how much oxygen they consume,

how much energy they actually consume,

by 75%, which is very similar

to what's happening in a rodent.

They have normal sleep-wake cycles,

they're much less active,

but they still do stand up,

and they may move around their den.

So, they're actually,

some of us in the bear world think that bears

are actually the most advanced hibernator based

on all of those abilities.

When you're studying hibernation in bears,

what does that actually look like?

So, I'm fortunate that I belong to a group

at Washington State University.

We have an actual facility with the sole purpose of trying

to understand everything about bear physiology,

bear ecology, and wildlife preservation.

We have these captive animals,

some which were raised in captivity,

others which came from the wild as problem bears.

And so those animals are hibernating right now,

and what we can do is we can go into those dens,

and we can sedate them them,

and we can take blood samples, for example.

We can take a small tissue biopsy to gather the cells

that we need for some of our cell culture work.

We can do a variety of physiological measurements

that we want.

Is there also a world in which we learn how

to hibernate as humans?

Because we know that hibernation evolved

in different species over different periods of time,

it's not unique to one particular class of mammals.

And I think humans potentially have some

of the building blocks that

we could use to induce hibernation.

Because of our body mass,

we could not lower our body temperature

to the point that a rodent does and be able to rewarm.

At this point, I see the bear

as being much more closely related

to a human type of hibernation.

Is there something we can learn about human physiology

by studying bear hibernation?

Well, I think so.

We've picked a couple of topics to focus

on in our bear work,

and one of them is what's known as insulin resistance.

It's something that diabetics will experience when

their bodies no longer respond to insulin,

and so the tissues can't take up

the glucose in the bloodstream.

Well, bears undergo this process normally

when they enter hibernation.

And so if we understood the mechanisms whereby

they can reverse that insulin resistance once

they come out of hibernation,

we might be able to apply that to a human situation.

The other thing that I think is very interesting

is this ability to lower the metabolic rate even though

the bears are at a relatively high body temperature.

And cancer cells are very active metabolically,

and so ways in which we could turn down

their sort of energetic usage might be a way

to limit some of the problems associated with cancer.

Heart rates decrease tremendously during hibernation,

but the bears don't suffer any cardiovascular problems.

They have no loss of bone density.

They don't lose any muscle mass in hibernation,

so there's a lot of interest in trying to understand,

in terms of people that are bedridden or in space travel,

the loss of muscle mass is considerable,

but bears seem to not succumb to that,

even though they're laying around for about 98% of the day.

You mentioned just there the prospect of learning

to hibernate as a way to get to Mars.

And I think this is one

of the sort of interesting applications

of hacking human physiology.

How would hibernation help with that effort?

And how do you see that playing out?

Yeah, the primary benefit there is

that it allows us to be able to use a spacecraft

that doesn't require carrying all the food

that's necessary to bring someone to Mars.

The passengers on the spacecrafts could actually enter

that state of hibernation and so be transported

for who knows how long,

maybe a couple of months even,

without having to eat anything.

You'd require less oxygen,

so you probably wouldn't need as much oxygen on board.

Of course oxygen is light, so that's not as big an issue.

And if we could lower our temperatures,

we would save even more energy.

What would human hibernation look like,

and why can't we hibernate already?

You would essentially be asleep.

Your brain activity would be sleep-like,

your blood pressure would be lowered,

and your use of energy,

much like what happens during sleep,

would also be greatly reduced.

Now, when we go to sleep our metabolic rate drops

by about 6% or so, plus or minus.

But hibernation is a much deeper level

of metabolic suppression, and those are the targets

and the pathways that we want to try to identify.

What makes it possible to go from a 6% reduction

in metabolic rate to 75% reduction of metabolic rate.

It may involve some lowering of body temperature,

and that's fine.

Those kinds of temperatures are actually used now

in humans for surgeries

and for doing organ preservation

and transplantation.

We know that by storing something

at a colder temperature actually allows it

to actually survive for a prolonged period of time.

There are of course limits to that,

but I think that the principle there

is gonna be very similar.

So is this feasible?

I think once we have a mechanistic picture

of what's going on,

and the genes and the proteins

that we identify are there in humans,

then I think it is feasible.

We don't have a lot of evidence to suggest

that hibernation is induced by one particular thing, right?

It's not there's this factor that appears suddenly,

the animal goes into hibernation.

It's malleable, it's flexible,

and it relies on multiple types of events occurring.

And I think as long as those pieces are there in humans,

then we could translate that into a situation

where hibernation could be induced.

Now, the question is would anyone,

would we want to hibernate for six months

if we weren't going somewhere, right?

And I think the answer is no,

unless it has some obvious benefit.

And I could envision, for example,

maybe someday being able to put someone

into a state of hibernation that has a terminal disease,

and maybe halting the spread of that disease,

or the development of that disease

until a cure is found.

These are all more or less science fiction things

at this point in time, but I think having

that ability would get us one step closer

to being able to do those sorts of things.

Now whether all the organs

would survive something like that,

these are all the questions that remain unanswered.

Thinking about humans hibernating

seems super science fiction-y.

Is this a new idea because of sort of ambition

to go to space, or is this something

that people have been thinking about for a long time?

This idea has been around for a really long time.

You see it in movies going back to the '50s. [laughs]

But what's changed over time is the development

of molecular, genetic, and other tools that allow us,

or potentially could allow us, to modulate

or modify our own physiology.

And those kind of things back

in the day were all science fiction,

and now they're science fact.

And it's wrapped up in a lot of ethical issues,

rightfully so, and so we need to be careful.

But I think the basic premise has been there

for a long time, and I think we've just,

we're getting closer and closer

with the development of these tools.

And I think by incorporating what we learn from animals,

as we've done so often,

we can apply that to humans to great benefit.

Who knows where this is going to lead us?

We're still at a very basic stage of trying

to understand, at the very molecular level,

what is really going on,

and what allows these transitions to occur.

And so taking that information into the next level

is gonna be a very difficult process.

Well, thank you so much for joining us.

Well, thank you for having me.