Brown fat (adipose) is a metabolically active tissue that dissipates energy as heat rather than storing it as fat. It helps humans acclimate to cold, and may be critical for weight maintenance. Researchers from the National Institutes of Health, led by Francesco Celi and Paul Lee, found a novel way of turning on brown fat and increasing caloric expenditure: sleep in a cooler room.
In the study, they had five men sleep in one-month blocks at room temperatures varying between 66 and 81 degrees. Researchers discovered that sleeping in the cold room doubled brown fat activity and improved insulin sensitivity and blood sugar regulation. Sleeping in a slightly cooler room (66 degrees) might be an effective way to increase metabolism and promote weight loss.
Source: Diabetes, Published Online June 22, 2014