Blood clots, bed sores, bone loss — there is a whole host of ailments bears and other hibernating animals appear to avoid. So doctors and veterinarians are probing their deep-sleep ability.

Ole Frøbert, a cardiologist, cozied up to his next patient, gently turning blood-filled tubes and placing the samples into a plastic bag.

But drawing the blood had been more difficult than Frøbert was used to, given the fat, fur and freezing temperatures.

“It’s not easy to puncture a bear vein,” he said. Normally a doctor who works at Örebro University Hospital in Sweden and Aarhus University in Denmark, Frøbert had snowmobiled and snowshoed into Swedish bear country, eager to answer the question: How exactly do bears survive their long winter snooze without dying?

Blood clots, bed sores, bone loss, muscle deterioration — there is a whole host of ailments bears and other hibernating animals appear to avoid during their torpor.

So doctors and veterinarians around the world are probing the deep-sleep ability of hibernators and using those insights to develop drugs to treat cardiovascular issues and other ailments in people.

Frøbert’s work to understand the mystery of bear blood is just the latest in a bevy of research into bears and other hibernating animals. Even space agencies and militaries are putting money into hibernation research in the hopes of harnessing discoveries to help astronauts endure the rigors of space travel and to treat injured soldiers.