Dr. Andrews noticed that hibernating squirrels use melatonin, a potent antioxidant, to protect the cells when blood flow increases after months of inactivity. His team put together a cocktail of melatonin and ketones that might be injected into a person experiencing hemorrhagic shock, to reduce damage to tissues when blood supply returns. The treatment so far has passed tests with rats and pigs, and the team has met with the U.S. Food and Drug Administration to plan future clinical trials.

The physiology of hibernation might also be applicable to organ transplants. A waiting kidney or liver can be preserved in cold solutions for 24 hours, but after that it can’t be used; a heart or a lung is only viable for four to six hours.

“Transplantations have to be very well planned out, and there’s no such thing as organ banks,” Dr. Andrews said. Individuals in need must wait for a donation. But if organs could be induced to enter something like hibernation, with a lower metabolic rate, that might allow organ donation banks to exist.