Too hot to sleep? How to cool down tonight

Why heat keeps you awake

In the evening, your body begins shedding heat through the skin, especially the hands, feet and face. That small drop in core temperature is part of the signal that it is time to sleep. In a hot room, there is less difference between your skin and the air, so heat leaves more slowly.

A 2012 review in the Journal of Physiological Anthropology by Okamoto-Mizuno and Mizuno summarized research on the thermal environment and sleep. Heat exposure increased wakefulness and reduced deep sleep and dream sleep, and high humidity made those effects worse because sweat evaporates less. In short, a hot, muggy bedroom works directly against sleep.

Cool your body first

1. Take a lukewarm shower about an hour before bed. Very cold water can make your body hold on to heat; lukewarm helps blood flow to the skin.
2. Cool your hands and feet. Run cold water over your wrists, or keep your feet out from under the sheet.
3. Wear less, and wear cotton or linen. Or sleep under a single thin sheet.
4. Use a damp cloth. A cool, damp cloth on your neck or forehead helps while you settle.
5. Drink water through the evening, not a huge glass right before bed, which can wake you later.

Cool your room as much as you can

• Close blinds during the day on sun-facing windows to keep heat out.
• Open windows once the outside air is cooler than inside, ideally on opposite sides of the home for a cross-breeze.
• Point a fan at you, and if the air is dry enough, place a bowl of ice in front of it.
• Move lower. Heat rises, so a downstairs room or even a mattress on the floor can be cooler.
• Turn off heat sources such as lamps, chargers and devices in the bedroom.

If you have air conditioning, setting it a little cooler than daytime comfort helps, and many people sleep best in a cool rather than warm room.

Your bedding matters too. Memory foam and thick duvets trap heat. On a heatwave night, swap the duvet for a sheet, use a thin cotton pillowcase, and flip the pillow to the cool side when it warms up.

Stay calm when you cannot settle

Hot nights invite frustration, and frustration raises your heart rate and body temperature even more. Instead of tossing, lie still on top of the sheet and slow your breathing. An exhale-weighted pattern such as the physiological sigh is quiet and needs no effort.

If your thoughts start circling, use a neutral imagery task like the cognitive shuffle. Some people find it helps to picture cool scenes: snow, a shaded forest, the inside of a fridge. It sounds silly, but it gives your mind something to hold besides the heat.

Extreme heat is a health risk, especially for older adults, babies and people with some health conditions. If your home is dangerously hot, look for a cooler place to sleep and follow local heat advice.