Human hibernation will no longer be science fiction

Human hibernation could become a reality in a few decades. ESA has already undertaken studies to bring it to space

The first human hibernation experiment could be feasible within a decade, reveals the European Space Agency (ESA). These experiments would pave the way for a science-fiction approach in long-duration space missions. Crew members put into a protective sleep for weeks or months would have fewer problems on their journey to distant destinations.

Hibernating during a one-year journey to Mars would not only avoid boredom in the space capsule but would also save on mission costs. With the hibernating crew, there would be no need to consume food or water, and it would also require a lower amount of oxygen. Moreover, research on animals suggests that the bodies of hibernating astronauts may deteriorate much less than awake bodies in microgravity conditions.

No longer science fiction

For all these reasons, hibernation, also known as torpor, has long been a staple in science-fiction space films. But today human hibernation may not be too far-fetched. Jennifer Ngo-Anh, a researcher in human and robotic exploration at the ESA and co-author of a recent article (ref.), has outlined the space agency’s approach to hibernation research. Depending on the availability of funds, the first tests could take place as early as the mid-2030s.

“We have to develop everything before we can apply it to humans. But I would say that 10 years is a realistic timeline” said Ngo-Anh. Surprisingly, the development is already underway, and the first studies have shown that hibernation (ref.) can be induced in rats and brought back to life a few days later. But the process of activating hibernation is quite complex and involves reduced exposure to daylight and a period of intense feeding followed by strict fasting.

“The rats are given a drug, a neurotransmitter, and brought into a dark space at reduced temperature” said Jürgen Bereiter-Hahn, emeritus professor of neuroscience and cell biology at Goethe University in Frankfurt. “It works very well, but the problem is that you have to repeatedly apply the neurotransmitter to maintain the state. You have to maintain very high levels of the molecule, and this could have long-term deleterious effects”.

Why is human hibernation important?

Researcher Ngo-Anh believes that torpor could be the only way to go if we want to undertake long-duration space missions. Space presents constant dangers to human health, with the loss of bone mass being a major problem in space. On the International Space Station (ISS), despite the presence of fitness machines and rigorous exercise protocols, astronauts lose up to 20% of muscle mass per month.

“This is a serious problem for astronauts in microgravity conditions” said Bereiter-Hahn. “Astronauts have to train a lot because otherwise, they would really have serious problems when they return to gravitational conditions”. Strangely, rest during hibernation does not seem to cause such effects. In fact, animals that wake up from hibernation show surprisingly high levels of fitness. “When animals wake up from hibernation, they quickly remember what surrounds them. In a few seconds, they remember where they hid their food before hibernation. They do not suffer much muscle loss, which is quite surprising after months of sleeping in a cave”.

Although hibernation superficially resembles sleep, at the physiological level, it works completely differently. Unlike a sleeping brain, for example, one in torpor produces little electromagnetic activity. Heart rate drops to a few beats per minute, and body temperature drops to hypothermic levels. Even cells interrupt their normal biological activity. The state of torpor is almost like pressing a pause button on life.

Importance of medicine

The hibernating astronaut in a capsule headed for Mars would not only save water, food, and oxygen. He or she would most likely wake up in good shape, without suffering the side effects of living in microgravity conditions. Furthermore, studies show that the slowed cells of a body in hibernation are not damaged by radiation, which is the main problem to tackle during space missions.

Although most current research on human hibernation is funded by space agencies and zoology institutes, many researchers believe that the first human being to be put in this pause state will probably be a patient in intensive care. Once the first human being survives and benefits from torpor, the technique will progress much faster.

“As has always happened in medicine, you have to have the first human being subjected to these conditions” said Alexander Choukèr, professor of medicine and anesthesia expert on the ESA team. “At some point, there is a number one case where you apply because the risks and benefits are in balance and lean more towards the subject’s benefits. And then you can start from there. We perform anesthesia every day, but we still don’t understand how it works 100%. Nevertheless, we have acquired a lot of knowledge in the last 20 years. Certainly, when they started applying anesthesia for the first time, there was no real idea of how it worked”.

Researchers, however, agree that for hibernation to be useful in space flights, it should work without complicated life support machines. The journey from patient one to a trip to Mars may therefore take a little more time.

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