JOHN YANG: Bears aren't the only animals settling in for their winter hibernation right about now.

Arctic ground squirrels can lower their body temperatures to freezing levels and stay dormant for up to eight months.

Researchers at the University of Alaska in Fairbanks are studying how these squirrels can survive on the edge of life.

And as public Alaska Public Media's Kavitha George reports they may hold the clues to treating injuries and disease in humans.

The story was produced in collaboration with Nova with major support from the Corporation for Public Broadcasting.

KAVITHA GEORGE, Alaska Public Media (voice-over): This little squirrel just came out of a lab freezer, but it's not dead.

And scientists like Sarah Rice want to know why.

SARAH RICE, University of Alaska Fairbanks: There's no cardiac arrest.

There's no stroke.

They're obese, but there's no ill effects.

There's no bone loss.

KAVITHA GEORGE (voice-over): This is an Arctic ground squirrel and during hibernation, it can chill its body down to the freezing point, 32 degrees Fahrenheit.

It's the only mammal that we know can get that cold.

SARAH RICE: And they wake up and they're just fine in the springtime.

KAVITHA GEORGE (voice-over): Here at the University of Alaska Fairbanks researchers are trying to understand the biological mechanisms that allow squirrels to withstand such extreme conditions and bounce back completely healthy.

They found that when the squirrels hibernate, they cycle in and out of a deep sleep called torpor.

SARAH RICE: They're in torpor for weeks at a time where they're super, super cold.

The heartbeats maybe five times a minute, they breathe once a minute, and they're just inactive.

KAVITHA GEORGE (voice-over): Arctic ground squirrels are found all over Alaska, Siberia and parts of Canada.

They hibernate because harsh winters limit their ability to find food for much of the year.

But every few weeks, they slowly warm their bodies to make glucose proteins and immune cells, basically everything their bodies need to do to keep living.

So how do they do it?

If researchers here can figure it out, it might help them develop drugs that can mimic hibernation in humans.

Biologist Kelly Drew says hibernation might help patients with critical brain injuries, like someone who's just had a stroke.

Scientists have known for decades that lowering body temperature helps to slow brain damage.

KELLY DREW, University of Alaska Fairbanks: The optimal therapy for somebody who has a brain injury is to either stop fever, or to cool the body.

And the best way to do that is through the same mechanism that the ground squirrels do to turn down the thermostat.

KAVITHA GEORGE (voice-over): Drew's small team of scientists is working on creating a drug to chemically turn down the body's thermostat like squirrels do in hibernation.

They're focused on certain receptors in the brain called adenosine A-1 which Drew found play a role in slowing the squirrel's metabolic rate and lowering their body temperature.

Her hope is that a drug that stimulates A-1 receptors in human brains to induce body cooling could be part of an effective treatment for stroke or other brain injuries, or even promote brain health as we age.

KELLY DREW: The other thing that cooling and rewarming does to the brain is it also creates these regeneration of synapses and maybe even neurons.

And so for things like mental health, I think cooling and rewarming could be remarkable because it promotes plasticity.

Same with neurodegenerative diseases like Alzheimer's.

KAVITHA GEORGE (voice-over): So far, Drew says the drug has shown promising results in rats and pigs.

The drug testing process is long and rigorous.

If it works, it could be five to 10 years before it has final FDA approval for human use.

Drew says NASA has even shown an interest in the potential to put astronauts in a hibernation like state to aid space travel.

The seven-month trip to Mars would be a a lot more pleasant in a hibernation bubble.

For PBS News Weekend, I'm Kavitha George in Fairbanks Alaska.