Washington - American scientists have for the first time eased mice in and out of hibernation, a possible procedure for treating critically ill and injured humans, said a study published Friday.

Scientists at the Fred Hutchinson Cancer Research Center in Seattle, Washington, exposed the mice to high levels of hydrogen sulfide to put them into hibernation, suspending most metabolic activity, Science magazine said.

Later the mice were revived showing no significant ill effects, said the scientists.

"We are, in essence, temporarily converting mice from warm-blooded to cold-blooded creatures, which is exactly the same thing that happens naturally when mammals hibernate," said lead investigator Mark Roth.

"We think this may be a latent ability that all mammals have - potentially even humans - and we're just harnessing it and turning it on and off, inducing a state of hibernation on demand," said Roth.

In a hibernation-like state, cellular activity almost stops completely, reducing the organism's need for oxygen.

Applied to humans, this could gain valuable time for critically ill patients in operating rooms, injured soldiers on battlefields, and those awaiting organ transplants, according to Roth.

It could help people suffering from severe fever, and also possibly help in treating cancer, by protecting normal cells during radiation and chemotherapy, according to Roth.

For the mice, the artificial hibernation was induced using hydrogen sulfide, a chemical normally produced in humans and animals that scientists believe helps regulate body temperature and metabolic activity.

The mice' respiration and temperatures plunged drastically as they appeared to lose consciousness, the study noted.

They were then revived with little apparent effect.

Roth and his colleagues said the technique could possibly be used within five years to help people suffering severe fevers of unknown origin.

"Here's a patient group, quite commonly found in emergency rooms around the country, who would do well if they could just have their core body temperature taken down in order to buy them time until the pathology reports come back and they can get on the right course of treatment," Roth said.

"Today, physicians have no way of dealing with uncontrolled fever other than literally putting people on ice. Well, we believe we know how to flip the breaker on the patient's furnace. If they have a fever, we believe we know how to stop it on a dime."