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 around 18.5 degrees, 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 London. 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.