The Secrets of Longevity: Torpor in Hibernation May Slow Aging

As temperatures cool and then dip below freezing, some animals hurry to store enough fat to last through the winter as they hibernate. Now, scientists have taken a closer look at hibernation and have found a link between time spent at higher temperatures and aging.

Offspring of dormice that are born late in the year have far less time to store fat reserves than those that are born earlier. Like other hibernating animals, dormice enter "torpor" in order to save both energy and water. In this state, dormice become inactive and show a marked decrease in their metabolic rate which, in turn, causes their body temperature to decrease.

And yet dormice don't only enter torpor during hibernation. Torpor is a strategy that these animals can use when food availability is limited. In order to see how mice born late in the season cope with conditions as winter draws near, scientists examined two groups of juveniles born late in the season. One group was able to feed freely and the other group intermittently fasted on alternate days.

"Torpor was only viewed as a means to save energy and water, but during the last decade other functions have emerged," said Sylvain Giroud, the lead researcher of the study, in a news release. "These include promoting growth during early life and fattening prior to hibernation, as well as slowing aging processes."

In fact, the researchers found that torpor and hibernation were associated with slowing aging processes and increase of longevity. The scientists discovered evidence for a functional link between time spent at high body temperature (euthermic) and aging processes over the winter.

Currently, the scientists hop to continue their research by comparing late-born juvenile dormice with their early-born counterparts. They suspect that the early-born dormice will use less torpor, grow at a lower rate and reach higher fat levels prior to winter hibernation. The researchers also hope to investigate the impact of lower growth rates and higher pre-hibernation fattening on aging.

"We hope to unravel the mechanisms involved in torpor use and aging processes in individuals facing contrasted environmental conditions during their early life," said Giroud.

The findings are published in the journal Proceedings of the Royal Society B: Biological Sciences.