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Chill Out: Sleeping in Cooler Temperatures May Increase Your Metabolism


Want an excuse to crank up the air conditioning?

A new study found that when men slept in cooler conditions, it gave their metabolism a boost. "Just by sleeping in a colder room, they gained metabolic advantages," says Francesco S. Celi, MD, lead author of the study.

Researchers with the National Institutes of Health recruited five men to sleep in climate-controlled rooms for four months, during which time they adjusted the temperature. After sleeping for a month in a 66-degree room, the lowest setting tested, the subjects had more brown fat in their bodies, which researchers say is the key to the metabolic improvements.

The term "brown fat" might not sound appealing, but its effects are. "It's metabolically active fat, unlike white fat," says Timothy E. Graham, MD, an assistant professor of medicine, biochemistry and nutrition at the University of Utah and director of the University of Utah's Diabetes and Heart Disease Prevention Program.

White fat is more of a storage fat, while brown fat burns calories to help the body maintain its core temperature. Brown fat is more prevalent in babies because they need it to help stay warm, according to the National Institutes of Health, but it's now known that adults retain some in the neck and shoulders. Although the five men in the study didn't burn enough calories to lose weight, the additional brown fat prompted metabolic changes that lowered their risk for diabetes.

The effect only lasts as long as you sleep in a cooler room, though. The researchers found that after four weeks of sleeping at 81 degrees, the metabolic enhancements were undone. In fact, the men then had less brown fat than after the first scan.

Graham says that even if you're not one for running the AC all night, just getting enough sleep can be a boon for your metabolism.