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Do you ever feel so tired that you want to sleep for a few months? Scientists are searching for ways to cause human hibernation.

Hosted by: Olivia Gordon
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Olivia: Ever woken up on a cold morning and wished you had five more minutes in bed? How about five days, months, or years of slumber?

Lots of researchers have been contemplating that question too, and not just after a hard day in the lab. Figuring out how to get humans to hibernate could be a life-saving therapy... and maybe even let us travel to distant worlds someday. Helping us with this research are two unlikely assistants: fat-tailed lemurs and hydrogen sulfide – the molecule that brings you that lovely smell of rotten eggs.

Hibernation is an energy-saving strategy that lets animals stick it out through the tough times – like cold or dry seasons when less food is available. All kinds of creatures hibernate. But it’s not the same as sleep, which has characteristic brainwaves and eye movements.

Hibernation is more of a general slowdown – a long period of inactivity combined with lower metabolic rate and body temperature. Some animals, like Arctic ground squirrels, go all out. Their core temperatures can drop below zero degrees Celsius for three weeks straight.

Now, humans obviously aren’t doing this temporary shut-down thing on a regular basis. But there have been anecdotal tales of people dropping into a deep hibernation-like stupor and surviving extreme conditions. One Japanese hiker, for instance, fell and broke his hip, lost consciousness, and lasted 24 days out on a mountain without any food or water. And it looks like, genetically, we probably have everything we need to hibernate.

Fat-tailed lemurs in Madagascar hibernate for up to eight months a year during the dry season, living off the fat reserves stored in their tails. They may be smaller and furrier than us, but they’re primates, and we share 97% of our genes.

Scientists looking into this don’t think there are special hibernation genes hiding in that 3% of DNA that doesn’t overlap. Instead, lemurs seem to be able to hibernate by controlling which genes are turned on or off. For example, while they’re slumbering away, lemurs somehow turn up genes involved in breaking down fat, and turn down genes that process carbs. If researchers could figure out how to cause human bodies to hibernate, by dialing genes up or down, or something completely different, it could be a super useful tool in medicine.

Hibernation means organs need less oxygen to function, breathing slows down, and the heart doesn’t have to pump as fast. So like, if someone’s in a really bad car crash, they would lose less blood if they were put into a hibernation-like state. Plus, any organs that wouldn’t be getting enough oxygen because of all that bleeding, would need less oxygen to stay healthy. So, overall, they wouldn’t suffer as much damage.

Severely injured people could stay alive longer, and it would give emergency responders more time to get to a medical center. So, if we’re really like lemurs, and our hibernation potential is just lying dormant within us, how could we coax it out?

It turns out that one possible solution is hydrogen sulfide. That’s right, the chemical that stinks like rotten eggs could help us hibernate. At least, it can do it for mice.

Like us humans, lab mice aren’t natural hibernators. But when they’re exposed to hydrogen sulfide gas, mice have entered a suspended-animation-like state, and survived for hours in low-oxygen environments that would normally kill them. Hydrogen sulfide does a lot of things to animal bodies, and in large amounts it can be deadly.

We know it can bind to a key enzyme in mitochondria, which are structures inside cells that make chemical energy. When hydrogen sulfide molecules bind to this enzyme, they block out oxygen. And that could contribute to a shutdown of these powerhouses, lowering metabolism and triggering a sort of hibernation. To wake the mice up, all scientists needed to do was to remove the hydrogen sulfide supply. The mice came to, and seemed fine, without any behavioral or neurological problems.

Just because it works on mice, of course, doesn’t mean it’ll work on people. But think of the possibilities! If space colonization ever kicks off, putting astronauts in a suspended animation could make the journey a whole lot easier – and save on food and other resources. Even if it just worked on individual human organs, that could be a huge step in medicine, and make the organs we transplant healthier, and extend their shelf-lives.

Now, even if researchers figure out how hydrogen sulfide or some other treatment can send us into a long sleep, there are still other issues that would need to be ironed out before we have fully-functional “stasis pods.” Like, human bodies aren’t well adapted to staying still for extended periods. They tend to get blood clots, which are really dangerous and can lead to death. And people on long bed-rest and astronauts in low gravity tend to lose muscle, and their bones weaken. So even if humans could be made to hibernate, we’d have to figure out how to keep our bodies healthy too.

So, there are plenty of tests and tweaks to do before patients get better, hibernation-based therapies in the ER or we’re blasting off resting astronauts into space. But as we learn more, human hibernation is looking less like a sci-fi fantasy and more like actual science.

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