There's nothing more frustrating than slipping into a set of hot, sticky sheets and tossing and turning all night in a warm bedroom. And, it turns out, there's a scientific reason your body sleeps poorly in a hot bedroom. It's a smaller temperature gradient—or the difference between your core body temperature and the room temperature—that triggers a sleepless night. The optimal gradient is the difference between your core body temperature, 98.6 degrees Fahrenheit, and about 68 degrees, the temperature sleep experts say provides an optimal sleep environment. As part of the body's natural rhythm, our core temperature drops about half a degree at night, signaling bedtime. And it seems that a cooler bedroom helps to make this dip happen.
But you don’t need to sacrifice a good night’s sleep just because you can't crank up the A/C. We talked to Michael Decker, Ph.D., a member of the American Board of Sleep Medicine and laboratory director at Case Western Reserve University’s Frances Payne Bolton School of Nursing, and Philip Gehrman, Ph.D., from the Penn Sleep Center at the University of Pennsylvania, to get their tips on the best ways to beat the heat and catch some Zzs.
Keep the blinds closed. Though a sun-drenched room sounds lovely, in reality it can turn into an oven during the summertime. To keep the room cooler, simply close the blinds during the day, Gehrman says. Blocking out sunshine and heat means a cooler atmosphere when it’s time to sleep.
Eat a small meal. Eating a feast right before hitting the hay kicks your metabolic system into high gear digesting calories. And expended energy raises your core body temperature. Gehrman suggests curtailing eating within an hour-and-a-half to two hours before bed—if you're hungry, try sticking to a piece of fruit, a small bowl of cereal, or some cheese and crackers to keep your metabolic rate and body temperature in check so you'll still feel sleepy.
Get a dehumidifier. The humidity level rises during heat waves, which adds to the discomfort level of a room because sweat accumulates on your skin. Decker says using a dehumidifier squeezes the moisture out from the air, making it feel less “heavy” so your sweat can actually evaporate into the air (since it’s not packed with moisture).
Take a hot bath. This seems counterintuitive, but Gehrman says to take a hot bath before bed. Upon getting out, if your skin temperature is hotter than the room you’ll experience a drop in body temperature as heat transfers out. And that'll help you to feel sleepy. If you have a newborn, take note: Babies' thermoregulatory systems aren't as efficient as adults', so this is an easy way to keep your child cool.
Surround yourself with breathable fabrics. If you’re not comfortable stripping down, make sure your pajamas are made from light and breathable fabrics like cotton, hemp, and linen. Have a foam mattress top or pillow? Decker says to put it away. Foam absorbs heat, making you feel like you’re sleeping in a hotter bed.
Stick your feet out of the covers. The body dissipates heat through the scalp, skin, and soles of our feet—anywhere with lots of blood vessels where heat can be released. Decker says sticking your feet out from under a blanket allows you to trap and direct heat outwards.
Sleep in the basement. Though it's common sense by now, it’s still worth repeating. Heat rises, so if you live in a multi-floor house and your bedroom is on the fourth floor, you can count on the heat being settled there by the time you go to sleep. Gehrman says the basement or the first floor will be the coolest in the house, so sleep there if you can.