Scientists are racing to unlock the secrets of hibernation in animals, aiming to recreate this biological state in humans to enable deep-space travel to Mars and beyond. The European Space Agency (Esa) and Nasa are funding research into synthetic torpor, a controlled metabolic shutdown that could protect astronauts from radiation, muscle wasting, and psychological stress during long voyages. This technology also holds promise for treating medical emergencies on Earth, such as strokes and organ preservation.
Why Hibernation Matters for Space Travel
Long-term spaceflight poses severe health risks. Extended exposure to microgravity damages muscles, bones, and eyes, while space radiation—unblocked by Earth’s atmosphere—can harm DNA and increase cancer risk. Psychological strain from confinement adds to the challenge. Hibernation, a 250-million-year-old strategy used by mammals, birds, and fish, could mitigate these hazards by drastically reducing metabolic needs. During hibernation, animals do not eat, drink, or move, and they resist cold and radiation damage.
“This is a very promising area,” says Christiane Hahn, who oversees space biology research at Esa. “It could absolutely transform the future of space travel.”
Radiation Protection and Metabolic Shutdown
Radiation is a critical concern for missions to Mars. In space, harmful ions penetrate spacecraft, posing continuous danger. Hibernation offers a natural defense: animals reduce metabolic activity, use less oxygen, and compact their DNA strands, which shields against radiation. They also possess potent DNA repair mechanisms. Elena Gracheva, a physiologist at Yale University, studies 13-lined ground squirrels, which hibernate for up to eight months without drinking. “Their heart rate drops to one beat every several minutes, and their body temperature goes to 4C,” she says. “Yet they’re still alive.” Gracheva has identified a brain region, the subfornical organ (SFO), that regulates thirst during hibernation, and a molecule that can abolish thirst when injected into the SFO—a pathway that may exist in humans.
Inducing Synthetic Torpor in Humans
Humans are not natural hibernators, but researchers are exploring ways to induce synthetic torpor—a state of reduced metabolism lasting hours to months. Kelly Drew, a biochemist at the University of Alaska, studies arctic ground squirrels that hibernate from August to May, dropping body temperature below freezing. Her team found that myosin, a muscle protein, changes its energy use during hibernation to survive cold. “It is definitely feasible,” Drew says.
Recent advances include noninvasive ultrasound techniques, tested in animals since 2023. Matteo Cerri, a physiology professor at the University of Bologna, is working with Esa to test ultrasound-induced torpor in healthy human volunteers. “Inducing torpor is fairly well understood,” says Hahn. “Bringing someone out again is not. We need to make sure we get both parts right.”
Key Brain Circuits and Early Human Trials
MIT researcher Siniša Hrvatin has identified a preoptic neural circuit in hamsters that triggers torpor when activated. This circuit likely exists in many animals, including non-hibernators, suggesting it could be manipulated in humans. “Key aspects of the circuit appear to be conserved across different animals,” Hrvatin says. He plans to investigate whether this circuit exists in humans.
In a 2023 study, Clifton Callaway from the University of Pittsburgh gave healthy humans the sedative dexmedetomidine for five days, inducing a 20% drop in metabolic rate and 30% decrease in calorie consumption. While modest compared to hibernation, Callaway notes that even a small reduction would help on a Mars mission: “A trip to Mars requires about 300kg of food per astronaut. If you can reduce that by a quarter or more, that can add up.”
Medical Applications on Earth
Synthetic torpor could revolutionize medicine. It appears to trigger broad repair and regeneration across organs, hinder cancer growth, and make tumors more vulnerable to treatment. Researchers are exploring its use for Parkinson’s disease, heart failure, asthma, and obesity. A Dutch team led by Rob Henning at the University of Groningen isolated the molecule SUL-138 from Syrian hamsters, which shows protective and regenerative properties in non-hibernating animals. They have started a small human trial for Parkinson’s.
Callaway, an emergency room doctor, sees potential for strokes, heart attacks, and brain injuries, where slowing metabolism could buy time. Unlike medically induced comas, synthetic torpor would not require life support because the brain remains active. “The sky is the limit,” Henning says. “When I talk to my medical colleagues, I always say: ‘What is your problem? I’ll solve it with hibernation.’”
Timeline and Challenges
Opinions vary on when synthetic torpor will become a reality. Cerri predicts 10 to 15 years; Hahn thinks several decades. Most experts agree that first human use will be medical, such as organ preservation. Hrvatin suggests activating hibernation pathways could lengthen organ survival time. However, significant challenges remain, including understanding the full complexity of hibernation and safely reversing the state. Hahn warns, “We need to make sure we get both parts right.”
