Space Sleep: Can We Freeze or Hush the Body for Long Trips?

The idea of putting astronauts into a deep sleep or freezing them sounds like something out of a movie, but scientists are taking it seriously. In the story of “Project Hail Mary, ” a teacher wakes up on a ship miles away from Earth, but that fictional scene is just the tip of the iceberg when it comes to real research. In reality, researchers are looking at two main ways to slow the body during space travel: synthetic torpor and cryostasis. Synthetic torpor is similar to how bears hibernate; it reduces metabolism so the body needs less food and oxygen. Scientists have even managed to induce a torpor‑like state in rats by injecting drugs into their brains, showing the concept works in animals that don’t normally hibernate. For humans, a research group at the European Space Agency is working on turning this idea into reality. If it succeeds, astronauts could live longer in space and might even be more resistant to harmful radiation because lower oxygen levels can help protect cells. However, no human has yet entered a true hibernation state, and safety concerns keep the experiments on animals for now.The other option is cryostasis—freezing a person and then thawing them later. Nature offers clues: tiny animals like tardigrades can survive being frozen for years, and some salamanders and squirrels can endure sub‑freezing temperatures without damage. A German research team recently showed that mouse brain slices could regain activity after being vitrified at –196 °C, suggesting that reversible freezing might be possible in theory. But the biggest hurdle is preventing ice crystals from breaking cells when water turns to ice. If scientists can solve this, along with the toxicity of the chemicals used for vitrification, cryostasis could enable truly long space voyages. Until then, both approaches remain experimental but promising paths toward making interstellar travel a reality.