Can’t Sleep? Adjust the Temperature

If insomnia is a problem, maybe your bedroom is too hot or too cold. Both can affect sleep.

Medically Reviewed by Louise Chang, MD on March 29, 2010
From the WebMD Archives

Tony Roy is among the 30% of American adults with insomnia-related problems. “I can go to sleep, but I wake up three or four hours later,” says Roy, a 51-year-old philosophy professor at California State University, San Bernardino. When he sought help at the nearby Sleep Disorders Center at Loma Linda University Medical Center, he got advice that had never occurred to him: Pay close attention to your bedroom temperature.

For years, Roy had followed his energy-conscious wife’s suggestion to lower the thermostat. “It was quite cold in our house,” he says. “We used to sleep with the thermostat set at about 60. I used lots of blankets.”

Not enough, it turned out. The very first night Roy followed his doctor’s suggestion to push the heat up to a more comfortable 68 degrees, he got a much better night’s sleep. “I was able to go back to sleep when I did wake up,” he says.

How Air Temperature Affects Your Sleep

Experts agree the temperature of your sleeping area and how comfortable you feel in it affect how well and how long you snooze. Why? “When you go to sleep, your set point for body temperature -- the temperature your brain is trying to achieve -- goes down,” says H. Craig Heller, PhD, professor of biology at Stanford University, who wrote a chapter on temperature and sleep for a medical textbook. “Think of it as the internal thermostat.” If it’s too cold, as in Roy’s case, or too hot, the body struggles to achieve this set point.

That mild drop in body temperature induces sleep. Generally, Heller says, “if you are in a cooler [rather than too-warm] room, it is easier for that to happen.” But if the room becomes uncomfortably hot or cold, you are more likely to wake up, says Ralph Downey III, PhD, chief of sleep medicine at Loma Linda University and one of the specialists treating Roy.

He explains that the comfort level of your bedroom temperature also especially affects the quality of REM (rapid eye movement) sleep, the stage in which you dream.

What’s the Best Temperature for Sleeping?

Recommending a specific range is difficult, Downey and Heller say, because what is comfortable for one person isn’t for another (explaining how Roy’s wife slept blissfully in the chilly 60-degree room). While a typical recommendation is to keep the room between 65 and 72 degrees Fahrenheit, Heller advises setting the temperature at a comfortable level, whatever that means to the sleeper.

Roy plans to keep a close eye on the thermostat, even if the heat bills are a bit higher.

There are other strategies for creating ideal sleeping conditions, too. Experts from the American Academy of Sleep Medicine, for instance, advise thinking of a bedroom as a cave: It should cool, quiet, and dark. (Bats follow this logic and are champion sleepers, getting in 16 hours a day.) Be wary of memory foam pillows, which feel good because they conform closely to your body shape -- but may make you too hot. And put socks on your feet, as cold feet, in particular, can be very disruptive to sleep.

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H. Craig Heller, PhD, professor of Biology, Stanford University, Stanford, Calif.

Ralph Downey III, PhD, chief of sleep medicine, Loma Linda University Medical Center, Loma Linda, Calif.

Tony Roy, philosophy professor, University of California San Bernardino.

Nature, September 1999, vol 401; pp 36-37.

Breus, Michael, PhD, Good Night: The Sleep Doctor's 4-Week Program to Better Sleep and Better Health (Dutton, 2006).

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