Gretchen Reynolds, writing for the New York Times:
The cold temperatures, it turned out, changed the men’s bodies noticeably. Most striking, after four weeks of sleeping at 66 degrees, the men had almost doubled their volumes of brown fat. Their insulin sensitivity, which is affected by shifts in blood sugar, improved. The changes were slight but meaningful, says Francesco S. Celi, the study’s senior author and now a professor at Virginia Commonwealth University. “These were all healthy young men to start with,” he says, “but just by sleeping in a colder room, they gained metabolic advantages” that could, over time, he says, lessen their risk for diabetes and other metabolic problems. The men also burned a few more calories throughout the day when their bedroom was chillier (although not enough to result in weight loss after four weeks). The metabolic enhancements were undone after four weeks of sleeping at 81 degrees; in fact, the men then had less brown fat than after the first scan.
The message of these findings, Celi says, is that you can almost effortlessly tweak your metabolic health by turning down the bedroom thermostat a few degrees. His own bedroom is moderately chilled, as is his office — which has an added benefit: It “keeps meetings short.”
I want to see a study that recommends sleeping in a nice, warm bed.