Here's a midsummer nightmare: I don't have air-conditioning in my house, so every night I create a Dyson fan tornado and pray to make it to morning. Dramatic as that may sound, if you're someone who already has trouble sleeping, trying to do it when it's sweltering hot makes it all the more frustrating, and there's a scientific explanation why.
"Temperature is quite important for your ability to sleep, and that's an underestimated factor," says Matthew Ebben, PhD, assistant professor in the Department of Neurology and Neuroscience at NYP/Weill Cornell Center for Sleep Medicine. "Part of your biological rhythms include a cooling of your body as you're sleeping during the night," Dr. Ebben says.
Hot temperatures inhibit your body's ability to cool off during sleep like it wants to. "Exposure to high heat loads at night — particularly if there's high humidity — can significantly reduce the rate at which heat is released from the body," says Scott Hollingshaus, MD, clinical instructor of sleep medicine at the University of Utah's Sleep Wake Center. So, it might take you longer to fall asleep if it's too hot. High temperatures can also induce a stress response in your body that can disrupt your sleep, he says. A cool room, on the other hand, facilitates this temperature drop nicely, he says.
The ideal bedroom temperature is between 60 and 67 degrees, according to the National Sleep Foundation. So, what should you do if you don't have AC? "You buy an AC, that's what you do," Dr. Ebben says. While that's not economically feasible for everyone, there are some very good reasons why you should have an AC, especially if you live in an apartment in New York City. Last summer, a study conducted by WNYC found that while the air outdoors will cool down at night, the temperature inside of apartments tends to stay as hot as it was during the day, so if you don't have AC, it can feel like you're sleeping during the heat of the day.
That said, if you must sweat it out for the remainder of the summer, ahead are some expert (and anecdotal) tips for keeping your body cool throughout the night.
Don't sleep naked
Sure, Nelly was the one who first said, "It's getting hot in here, so take off all your clothes" — but he might have been wrong. Apparently, sleeping without any clothes on could make you even hotter.
"I've seen a lot of advice about sleeping naked," Sophie Bostock, PhD, a sleep expert at The Sleep Scientist, told Women's Health UK. "But this isn't super helpful as what you can actually find is if sweat collects on the body, and isn't whipped away by a moisture-wicking surface, like you get from clothing, then it doesn't help you cool." Instead, wear cotton or any kind of clothing with moisture-wicking fabric.
Take a shower before bed
Chances are, you're probably drenched in sweat and already considering a rinse-off before you climb under your sheets, but showering before bed can actually help you sleep, Dr. Ebben says. And you don't have to shock yourself with a freezing cold shower, unless you really feel like it. "Warm showers and baths have been shown to increase slow wave sleep," he says.
Slow wave sleep is considered the deepest stage of non-REM sleep, so it's pretty important. "If you heat up your body before you go to sleep, and then go to sleep in a normal temperature room, the data shows that you can increase your slow wave sleep," he says.
Do some light exercise
If you can stand it, a little exercise before bed may actually help you sleep, Dr. Ebben says. The old logic used to be that exercising before bed will wake up your body, making it harder to sleep, but that's not actually true. "Exercise before bed heats up your body, which can again help low wave sleep," he says. Just make sure you do a workout that's not too vigorous, and won't make your body so hot that it's more uncomfortable to sleep. Not sure what to do? Try an easy walking video, a 30-minute yoga flow, or a quick ab routine.
Get a fan
Obviously, if you don't have AC, you may want to buy a fan to keep you cool and provide some white noise, Dr. Ebben says. White noise can be helpful because it masks out the other sounds that might wake you up in the middle of the night. If you have a ceiling fan, Dr. Hollingshaus suggests reversing the direction so it spins counterclockwise to push hot air out of the way. And if that's not enough, my roommate's grandmother bought her a necklace fan that I would highly recommend for wearing around the house.
Use ice packs
Place cold compresses or ice packs wrapped in a towel on your pulse points, such as your wrist, ankles, behind the knees, and neck, and it will cool down your whole body, Dr. Hollingshaus says. Or you could slip ice packs inside your pillows to provide more of a chill, just make sure they don't leak, says Daniel Barone, MD, assistant professor of neurology at the NYP/ Weill Cornell Center for Sleep Medicine.
Try different bedding
Less is more when it comes to bedding, so you should reduce your covers as much as possible, Dr. Hollingshaus says. Cotton sheets breathe better than other fabrics, so it can be helpful to use those during the summer, he says. Personally, I use a summer-weight quilt from Brooklinen, because it's 100% cotton and very thin.
Find a pillow with a permanent "cold side"
There are a few companies out there using heat technology to make their fabrics stay cold, so you won't have to keep flipping your pill for the "cold side" phenomenon. The Bear Pillow and Nest Bedding's Cool Pillow are good options to test out.
Don't use memory foam
Memory foam can be insulating, so it will trap heat in your body, Dr. Hollingshaus says. If you can switch to a different type of mattress or remove your mattress pad for the season, that might make a big improvement, he says.
Sleep in the coolest room
Heat rises, so if there's any way to sleep in a lower-altitude room in your house, do it, because you'll probably be cooler, Dr. Hollingshaus says. If that's not an option, keep your curtains drawn in the room during the day to reduce how hot it gets, he says. "And try to keep the room as dark as possible; light creeping in the window can disrupt sleep," Dr. Barone says.
"Drink plenty of water prior to bed to counter the sweating you will do," Dr. Hollingshaus says. You may also want to avoid alcohol for four hours before bed, because it can dehydrate you in the middle of the night, he says.
Kick out your partner
More bodies in bed equals more heat, so avoid sharing a bed on really warm nights if you can, Dr. Hollingshaus says. If you must share a bed because you live with your partner, just make sure that you have the right bedding to keep two sweaty bodies cool.
Do some breathing exercises
It sounds trite, but if you're in bed and can only focus on the heat and humidity, it may be helpful to try doing a breathing exercise to take your mind off the temperature and calm you down. Not sure where to start? Consider the 4-7-8 breathing technique, which involves breathing in for four counts, holding your breath for seven, and exhaling for eight counts until you fall asleep.