How to Sleep When It’s Really Hot Outside

Experts typically recommend setting your bedroom thermostat to around 65°F (a little over 18°C) for optimal sleeping conditions. And if you’ve ever stared at the ceiling for hours on a hot, humid night, you know why: it can be really hard to sleep in a warm room.

Your body’s core temperature naturally fluctuates throughout the day, dropping at night and then rising again when you wake in the morning. “A lower body temperature actually facilitates sleep for us,” says Dr. Anita Shelgikar, a professor of neurology at the University of Michigan Medical School. “When it’s harder to maintain that lower body temperature, that can be disruptive to our sleep.”

Research backs up that point. A 2018 study found that a one-degree-Celsius increase in room temperature translated to about three fewer minutes of sleep, potentially contributing to reduced cognitive performance among college students living in un-air-conditioned buildings. Another paper, from 2012, found that heat impairs the kind of sleep your body needs to wake up feeling rested and refreshed. People are also less likely to sleep through the night in a hot environment, even if they’re tired enough to drift off initially, says Jennifer Martin, immediate past president of the American Academy of Sleep Medicine.

The most obvious solution is to use air conditioning to keep your bedroom cool, but that’s not an option for people living in the 12% of U.S. homes without it—and may not be appealing to those who use their units sparingly for financial or environmental reasons. If you fall in either camp, here are other ways to sleep well when it’s hot outside.

Trick your body

A scientific review co-authored by Shahab Haghayegh, a research fellow at Brigham and Women’s Hospital in Boston, found that taking a hot shower or bath an hour or two before bed can improve sleep. That warm environment can trigger physiologic changes that lower your core temperature and help you conk out, he explains. (The average bedroom isn’t hot enough to cause this shift on its own, Haghayegh says—even if it feels uncomfortably warm.)

Prepare your room before bedtime

If you don’t need to be in your bedroom during the day, Shelgikar recommends keeping the shades drawn to block some sunlight and keep the interior temperature as low as possible. And if you have AC but don’t want to use it overnight, it may be beneficial to run it shortly before you go to sleep so you can drift off while the room is still cool, Martin adds.

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Use a fan

Fans “do double duty. They keep you cool and they provide white noise, which masks environmental noise,” says Dr. Josna Adusumilli, a neurologist and sleep-medicine doctor at Massachusetts General Hospital. Opening a window can also help, as long as air quality allows. “Circulating air, even if it’s warm, does seem to help people sleep better,” Martin says.

Update your bedding

Adusumilli recommends buying sheets and pajamas in breathable fabrics like cotton and linen. If you share your bed with someone else, consider using separate covers, as is common in some European countries, Martin suggests. Doing so can be helpful if one of you sleeps hotter than the other—and, at the very least, may offer some physical separation on warm nights.

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Try quick cooling tricks

It’s not the most scientific tactic, but Shelgikar says some of her patients find it effective to cool off in front of their freezers for a few moments before bed. Cold compresses or ice packs can also help ease discomfort—but, she says, they’re unlikely to be as effective as a cool room.

Don’t forget general sleep hygiene

All the usual advice still applies when it’s hot outside, Shelgikar says. Try to maintain consistent sleep and wake times, follow a relaxing bedtime routine, avoid bright lights shortly before bed, and see morning sunlight to regulate your sleep-wake cycle and prepare for the night ahead.