can we really sleep our way to the stars?

Space travel is paradoxical. Getting to a new world is exciting. Exploring that new world is a joy. But getting to that new world will be a very boring, dangerous, dark slog through the vacuum of space even if your rocket can achieve a significant percentage of the speed of light. With warp drives still very much eluding our grasp, space agencies are wondering if there’s a way humans could just sleep their way through the boring part of the voyage with all the benefits that could bring, and millions are being spent researching the possibility.

It sounds perfect. You board a massive spaceship in orbit, see the Earth fade into the distance while enjoying your first few weeks in space, then crawl into your warm, cozy bunk, take a pill or have an injection, then, next thing you know, you’re stretching your legs as a new moon or planet starts to fill your windows. While you hibernate, your metabolism slows to a crawl, so your dietary needs are almost nil, and your cells acquire resistance to radiation as processes that would be disrupted take place so slowly, they can avoid damage in the first place.

Even better, you could potentially gain a few years of life expectancy in the process before you start the hard work of exploring the vast realms of the unknown, paving the way for humanity’s future. Let’s just say it’s a major plot point in Andy Weir’s hard sci-fi novel Project Hail Mary for a reason, although his version relies on artificial comas that can scramble subjects’ brains and doesn’t exactly work as advertised on a spaceship careering through the stars. And that brings us to the science behind human hibernation beyond the promotional brochure.

could humans actually hibernate?

You may be surprised to know that for all the research done over the last 60 years, no one has been able to put humans in suspended animation for more than a few weeks, and that was a process which involved very dangerous drugs that interfered with breathing, done on very few people who were critically ill or injured. There have also been cases of very short-term pseudo-hibernation in response to hypothermia, but that’s probably not a process we’d want to try to emulate in the vacuum of space.

Of course, human body temperature would drop during hibernation anyway, which a bit of a problem since our physiology resists it with shaking, which will need to be stopped by a drug that can calm muscles but can’t cross the blood-brain barrier to interfere with memory, critical autonomous functions, and breathing. And even if we’re successful at that, muscle atrophy will set in after a week of immobility which will need another cocktail of drugs or constant electrical stimulation to overcome. And then there are the blood clots and damage to the gut biome.

But if it’s so difficult for humans to be unconscious and immobile at lower body temperatures for more than a week, why do so many scientists insist that we should be able to figure it out? Well, simply put, it’s because a lot of other mammals in our family tree have the ability to do it, and we should still have the genes and enzymes in our bodies to make it happen in some way, shape, or form. It’s supposedly just a matter of figuring out how to activate these latent abilities and harness the many benefits.

why we’d want to hibernate here on earth

So, let’s say we figure out how to rebuild our gut biomes after a month or year-long nap, break up blood clots and keep muscles stimulated with some sort of nanotechnology, and our minds survive intact. We can now fly through the solar system with far fewer resources and supplies since our astronauts won’t need much while they’re asleep, which sounds cool. But what’s the benefit to humans here on Earth? Are we really going to need to be able to sleep for so long in a fast-paced world that demands we’re always active and productive? Actually, yes.

If we can crack human hibernation, medical treatments requiring induced comas with the many dangerous side-effects of heart and lung machines, feeding tubes, and invasive IVs can become a last resort, vastly improving patients’ chances of recovery after serious trauma in accidents or on battlefields, strokes, and even cancer treatments. Instead of only being able to hit the fast forward button on traveling through an alien, inhospitable environment, we could do the same when we’re trying to recover from a serious illness.

We wouldn’t have a hibernation season, and every long sleep would be medically assisted, as we’d still need food, water, and constant maintenance to survive it, but when the situation calls for us to enter suspended animation, we’d not only have the option, but it would be preferable to existing approaches to handling long journeys and invasive, intense medical interventions. At the same time, however, these ideas require a lot of hurdles to overcome, and human trials are only slated to begin late this decade, with many questions will unanswered.

why we’ll always need someone awake at the helm

There’s also another dilemma to consider. It’s probably more than fine for a patient undergoing intense therapy to be out for months at a time, but would we really want a very large and very expensive spaceship careening through the cosmos with everyone on board asleep? There have been a lot of movies on the subject and — spoiler alert — they seldom find our intrepid explorers in situations we’d describe as optimal. Over a long period of time, things will happen and there are only so much automated systems can do.

We couldn’t rely on mission control on Earth to fix things remotely either. Once you get to the edge of the solar system, it takes an entire day for a signal to make a round trip. If the health and safety of a semi-comatose crew is in the balance, you probably don’t want their only shot at survival to be delayed by days since critical commands and diagnostic analyses could only travel at the speed of light. By the time one problem is fixed, a lot of things to make matters far, far worse could well have happened with no one around to even know about them.

Certainly, we should keep pursuing the science of human hibernation to learn a lot more about our bodies and their evolution, and try to reap the medical benefits we covered above. But are we going to be putting people in pods and blasting them to Proxima Centauri considering all the externalities of space travel? That seems very unlikely and dangerous, even if we do figure out how to hibernate. The fact of the matter is that space travel is always going to be difficult and offer few easy, safe shortcuts. But that’s the cost of discovery and exploration. If we want to learn more about the cosmos, we’re going to have to fight the universe for that right.