Sleeping in the cold is not bad for you—it helps your metabolism, improves insulin sensitivity, and may even help to regulate certain kinds of insomnia.
According to the New York Times, sleeping in the cold affects your metabolism in subtle but important ways. It increases your deposits of brown fat. Brown fat is unique - unlike normal fat, it's metabolically active so it burns calories. The NYT also found that sleeping in the cold improves your insulin sensitivity - it makes your body slightly better at regulating body sugar. These changes are small but could decrease your risk of chronic disease like diabetes over time.
Why does sleeping in the cold increase deposits of brown fat? The mechanism might be not just the cold - the researchers at Virginia Commonwealth University responsible for the brown fat study think it might be the body's shivering in response to the cold that stimulates brown fat production. If you're sleeping in the cold but warming up with a heavy blanket, your body heat might not get low enough to enjoy the metabolic upsides.
Lower temperature helps people fall asleep - Time Magazine reports that the body responds in a dip in core temperature at the right time of day by thinking that it's time to go to bed. One way to trigger this dip is by taking a bath before you go to bed. The sudden drop in body temperature when you get out of the bath will flip the switch.
Sleeping in the cold may also help to regulate certain kinds of insomnia. Researchers in Australia determined that sleep onset insomnia, which affects people when they're falling asleep, can be curbed by medication that reduces core temperatures.
Once you're asleep, though, the cold might not be right for you. Ideal temperatures for maintaining a deep and healthy sleep are individual - for the elderly, they may be higher than those which buff your insulin sensitivity or up your production of brown fat. Get too hot, however, and you might experience less deep sleep, which is important for staying rested. Sleeping in the heat also may aggravate sleep apnea, which is a common condition later in life.
- increases deposits of brown fat
- improves insulin sensitivity
- decreases risk of diabetes
- may help with sleep onset insomnia