What Sci-Fi Gets So Wrong About Suspended Animation

The latest Avatar movie is continuing James Cameron’s box office dominance, but back in 2009, Jake Sully had to reach the distant moon of Pandora before he could have his profitable adventures on it. This problem was brushed aside by an early scene where our hero wakes from suspended animation. “In cryo, you don’t dream at all,” Sully’s voiceover says. “It doesn’t feel like six years. More like a fifth of tequila and an ass-kicking.”

Suspended animation is a staple of science fiction, one used to transport characters across vast reaches of space and time. Once the domain of magic (both Sleeping Beauty and Rip Van Winkle fall afoul of fairies), sci-fi began to coalesce around the idea of blending cold, sleep, and general technobabble to put humans on figurative or literal ice. Mary Shelley and H.P. Lovecraft toyed with the idea, and then comic books and writers like Arthur C. Clarke made it a staple of both soft and hard sci-fi.

Today, the trope is everywhere from Futurama to Halo. Sometimes, suspended bodies are central to the plot, like in Passengers or Kim Stanley Robinson’s Aurora. In other stories, it’s an incidental detail used to swat away the challenges of space travel. Sometimes, writers invent novel explanations — Buck Rogers is transported to the 25^th century by a mine-gas-induced coma — but lowering our body temperature is usually shown or implied, whether it’s Sully’s mention of cryo or Demolition Man literally freezing criminals. Usually, a frozen body is completely inactive, essentially comatose. And that means, usually, science fiction gets it wrong.

“Although hibernation is usually looked at in relation to winter or the cold, this is absolutely not necessary,” Professor Vladyslav Vyazovskiy tells Inverse. “This is really important to clarify. There are animals that can hibernate in the tropics.” And that’s just the tip of the iceberg. The science behind deep sleep is very real, advancing fast, and might soon be the stuff of science reality.

A Different State of Mind

Professor Vyazovskiy studies sleep physiology at Oxford, and is also part of a European Space Agency team working on the challenges of putting humans in suspended animation. He emphasizes that, first and foremost, stasis isn’t about temperature, but a reduction in metabolism.

“Suspended animation doesn’t require hypothermia,” Vyazovskiy says. “It’s mostly about physiological functions, when the organism consumes less oxygen and nutrients, and uses less energy for everything. If it’s cold outside, there will be some cooling, but that’s secondary. Bears cool down just a little bit, but their metabolic rate decreases by like 70%. They can spend an entire winter on their body fat store because their metabolism is so slow.”

And while sci-fi tends to portray stasis as a state with an on/off switch, research into bears, squirrels, and many other hibernating animals has revealed an entire continuum of physical and mental activity.

"Torpor and hibernation are very dynamic states,” Vyazovskiy says. “It's not like a coma, it's very exquisitely regulated. The animal can maintain its body temperature to within a fraction of a degree above room temperature. It's like a super-precise thermostat."

“Torpor and hibernation are very dynamic states. It's not like a coma, it's very exquisitely regulated.”

Torpor (essentially hibernation on the scale of hours) and hibernation are responses to hostile environments; cold weather is just famously hostile. In some ways, humans are the odd ones out for adapting with tools and shelter. But if you don’t have opposable thumbs and a big brain, torpor, Vyazovskiy says, is a “clever” strategy that makes “so much sense.”

So while you may have learned that bears sleep through winter, it may really be more like a lethargic state of sleep deprivation. Sleep, Vyazovskiy explains, is a “brain-centric” state defined by a degree of unresponsiveness and changes in your brain waves. While changes to metabolism are minor during sleep, they’re significant during torpor, because it’s a mechanism for surviving poor weather or a lack of food. A pet hamster, for example, can enter torpor if it misses a few feedings or is put in a drafty room. Spend weeks or months in torpor, and you have hibernation.

“You can be asleep and hibernating, but we’re interested in the states of awareness during torpor,” Vyazovskiy says. “You can be awake and hibernating, animals can move around and look at you. It’s not sleep at all.”

Ground squirrels, for example, survive winter by hibernating in burrows, but Vyazovskiy explains that “every week or two they spend a tremendous amount of energy to reach a normal temperature.” They use some of this time to snack, but mostly, they sleep.

“They spend a lot of time sleeping during these episodes,” Vyazovskiy says. “They emerge from torpor, there’s a theory that they get tired of hibernating.”

Hypothetical human hibernation, therefore, would look a lot different than just shoving Jake Sully in an ice box for six years. How would it work, and why would we bother?

Dreaming Our Way to Mars

Space is the most hostile environment of all, and inducing torpor in astronauts would come with several benefits. The most obvious is that a human with a reduced metabolism needs to eat and drink much less, conserving valuable resources in the days before Mars gets its first 7-Eleven. Vyazovskiy notes that torpor would also protect against muscle decay caused by zero gravity, as well as cosmic radiation.

“When your metabolism is slow, there is less DNA replication and cell division. These processes can be influenced by radiation, which can induce mutations or toxic byproducts,” he says. “When you slow down metabolism, the organism becomes more protected.”

This is why suspended animation also has some hypothetical terrestrial applications, like protecting a cancer patient undergoing radiotherapy from the worst side effects of large radiation doses. It might also have uses in mental health treatment, as “a way of resetting the brain.”

“Torpor is a very dramatic condition, we know there’s a lot of synaptic reorganization,” Vyazovskiy says. “It’s almost close to what we find in an early age, when we have critical windows for plasticity and learning. If we understand torpor and what happens in the brain better, maybe we can use it in some clinical applications."

“We’re really interested in this very paradoxical state where you're very close to dying, because you have very little brain activity, but you're also very sensitive.”

But it’s space exploration that most captures the big-screen imaginations. Vyazovskiy notes that while sci-fi usually shows bodies being kept at very low temperatures, reality will likely be “a bear-like condition, where you cool down slightly but mostly just need to find a way to reduce metabolic rates.”

Pop culture has produced a few interesting exceptions to cryosleep. “The Three-Body Problem,” Vyazovskiy says, “depicts suspended animation in a very creative way where the body is desiccated, it loses all its water. In reality, animals in hibernation aren’t thirsty, water is almost aversive to them for reasons we don’t understand. There’s an interesting link to maintaining an osmotic balance, although obviously it doesn’t go to such an extreme as described in Three-Body Problem. But it’s anything but cryo, cryo will not be applicable.”

So, how would Vyazovskiy suggest portraying suspended animation if James Cameron came calling about tips for Avatar 4?

“Sleep and torpor are on a continuum, so you could make the entrance into hibernation via sleep. It could be more intense, deeper in some ways. But when animals are in torpor, they're much slower, and what we’re discovering now is that they become very sensitive, because if a predator is approaching, they need to detect it early. We’re really interested in this very paradoxical state where you're very close to dying, because you have very little brain activity, but you're also very sensitive. I would depict this somehow, being connected and disconnected to the environment at the same time.”

And Sully’s comment about not dreaming? That might not be true either. Dreaming is its own field of study with many unsolved mysteries, but as far as we know, there’s no reason dreams can’t occur during hibernation. If sci-fi wants a fresh take on the subject, maybe an interstellar journey won’t be interrupted by rogue AIs or bloodthirsty aliens, but strange dreams — or even implanted ones, a la Total Recall.

If we do take the eight-month trip to Mars in the coming years, hibernation likely won’t be a part of it just yet. Torpor has been artificially induced in rats, which don’t normally experience it, but Vyazovskiy says there’s still much to discover, including how animals “know” to spontaneously enter and maintain torpor, and how a human could safely be brought out of it. Still, there’s nothing about our size or energy needs that precludes the possibility; it’s even been suggested that maybe we used to hibernate before we tamed fire.

"I believe human hibernation is possible,” Vyazovskiy says, “simply because it's a really widespread phenomenon found across the animal kingdom. It pushes the boundaries of where we think our brain can function. And I really hope there will be more research, because it is absolutely unique and interesting.”