When it’s hot, sleep can be nearly impossible.
Kicking off the covers or sleeping naked can solve a lot of heat problems, but when the temperature is that hot — think 90s and up in Fahrenheit — it won’t matter unless you have air conditioning or are actively working to keep your body temperature down.
That’s because there’s a small but stark difference between hot sleep and sleeping with heat exhaustion.
“We can experience heat exhaustion even in our sleep,” says Alex Savy, certified sleep science coach. “The direct effect of heat exhaustion on our sleep is frequent wakefulness or restless sleep. Although this sign is the same for when you experience hot sleep, they are actually different phenomena.”
The wakefulness that heat exhaustion causes may interrupt your brain while it’s sending hormones to tell your kidney to retain water, making you more dehydrated when you wake.
“In the case of hot sleep, the temperature shed by our body is being absorbed by the material of the bed,” explains Savy. “[With heat exhaustion], a high environmental temperature will make the body dehydrate easily.”
While research shows dehydration is also associated with shorter sleep time and sleep deprivation (as well as more exhaustion), sleeping through a heat wave without extra hydration can further dry you out.
When it comes to avoiding and managing heat exhaustion, keeping your body cool throughout the day makes for a much better night of hot sleep. “[And] the best way to prepare for heat waves and heat exhaustion is by hydrating,” Savy says.
By hydrating, you’ll allow cooling products to actually work at night and enable better sleep because your body temperature is down. Here’s what you should do throughout the day to help maintain your regular sleep schedule.
What to do the day before a heat wave
Adjust your schedule to work during cooler times. Get your most physically taxing work done before the temperature ticks too high, and then focus on less-pressing tasks. Make a point to sleep earlier the night before, so you can wake up earlier. For example, if you need to work out or walk your dog, set a timer to wake up an hour or two before the temperature goes above 80 degrees, to make it less dehydrating.
If you live in an area where the sun takes forever to set, making enough time to do tasks while it’s cooler out will help you sleep on schedule. Doing active and energizing tasks at night, like exercising, tends to shift your sleep schedule to later.
Keep the stoves off and kitchen door closed, when possible
There is a reason no-cook recipes trend in the summer: Use of stoves and ovens can increase the temperature throughout your home during a heat wave. Not only is it too hot to eat anything that isn’t keeping your body temperature down, even opening your refrigerator door can increase the temperature of the kitchen, because it makes your fridge work harder, making a small living space insufferable.
Prepare hydrating foods
Eating enough at regular mealtimes is a challenge during a heat wave. Heat can dampen a person’s appetite. A 2019 study found that when you exercise in the heat, compared to the cold, your appetite will also decrease. Hunger that strikes and is fed when it’s cooler could also delay your bedtime.
Keep cold and hydrating fruits and vegetables around to snack on throughout the day, even when you’re not hungry. Cut up carrots, radishes, and cucumbers and make an appealing dip, like ssamjang. This salty, sweet, and spicy Korean sauce takes less than two minutes to put together and is also diary-free, so you didn’t have to worry about it sitting out all day. Hummus is another great, easy option.
If you really plan ahead, cold udon is a delightfully filling meal, as is pasta salad. Smoothie bowls that you can slowly sip and eat throughout the day will also help keep you hydrated and cool.
Nap earlier in the day
If you are already not sleeping enough in your day-to-day, naps during a heat wave are a must. Signs that you’re in need of a nap can include heavy eyelids or losing reading comprehension. Look for the coolest area of the house, usually the only room with an AC unit, or one with fewer windows, and nap no more than 30 minutes.
A small study in Japan that looked at sleep deprivation and heat exhaustion found that naps after lunch can help. Those who took naps reported faster reaction times and feeling less fatigued and overheated.
Take a cold shower
The often-shared tip is to take a hot shower before bed so your body temperature drops when you get out of the shower. However, with heat exhaustion, a hot shower will do the opposite — it could even put you in danger of fainting in the bathtub.
If taking a cold shower makes you feel more alert, take one after your midday nap.
No cooling products yet? Sleep with a wet or frozen towel
If you didn’t get your fans and cooling sheets shipped out in time, run towels under cold water (squeeze excess water out!) and use them as a blanket to keep your body temperature down.
You may wake up at some point in the night, when the outside temperature finally drops, to throw the blanket off, but overall this tactic results in a better night’s sleep because you’ll actually be able to fall asleep.
If you have the space (and time), you can also throw a towel, your pillowcases, and other sleep gear in the freezer. A chilled pair of socks could also do the trick if you can’t fit larger items in. Freezing your clothes and sheets is less damaging to your mattress than wet materials, especially if you don’t have a mattress protector.
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Be aware of heat exhaustion and heat stroke
Heat exhaustion is no joke. It can make you feel tired and think you’re not getting enough sleep. If you don’t connect your daytime sleepiness to heat exhaustion, you could unknowingly start to overcompensate in the sleep department. Research shows too much sleep can have a similar effect as too little and result in impaired ability to tackle mental and emotional tasks.
And it doesn’t have to be 100+ degrees to be considered hot. Your body can take time to regulate and adjust to the varying temperatures of a new place. Don’t make the mistake of believing heat exhaustion is over, just because the temperature dropped a few degrees.
Here are the signs of heat exhaustion:
- feeling disoriented or dizzy
- stomach, arm, or leg cramps
- extreme thirst, sweaty, or pale and clammy skin
- fast heartbeat or breathing
- feeling nausea or lack of hunger
When experiencing these symptoms, you should cool yourself immediately, otherwise you run the risk for heat stroke. Heat stroke is considered an emergency, so as you wait for help, cool yourself down by any means possible.
One trick is to pay special attention to how water feels when you wash your hands or take a drink. If the feeling of tap water is the most refreshing sensation, it may be time to focus on cooling down. Not only will this combat serious overheating, but the better you regulate your body temperature during the day, the more likely you'll be able to be productive — both at work and at home — and avoid the dreaded cycle of revenge bedtime procrastination at night.