Scientists have been able to induce reversible hibernation in mice. Using the gas hydrogen sulfide, the scientists were able to induce a state of hibernation within minutes. The mice slowed their metabolism down dramatically, from 120 breaths per minute to 10, and dropped their body temperature from a normal 37C (98.6F) to as little as 11C (51F).
While the article mentions many possible uses, as an old-school Sci-Fi fan, I have to take them to task for not mentioning the possible applications to space travel. If hibernation is possible, it may make longer-term journeys to destinations such as Mars and the outer planets a much easier proposition.