Rising temperatures often disrupt sleep. Hot nights can make it difficult to fall asleep and cause you to wake up more often during the night, making you less rested the next day.
One reason for this is thermoregulation, the body’s ability to maintain internal temperature within a safe range. Sleep is closely related to body temperature. In order to fall asleep and stay asleep, your body typically needs to lose some heat. This becomes difficult when the bedroom is hot.
And British summers are getting hotter. The Met Office reports that the chance of temperatures exceeding 40C in the UK is now more than 20 times greater than in the 1960s, with a 50% chance of another 40C day over the next 12 years.
Moisture can make the problem worse. Research on humidity and heat stress shows that high humidity can increase the strain that heat takes on the body. The body is partially cooled by sweating. As sweat evaporates from your skin, heat is taken away. However, if the air is already moist, evaporation will be less efficient.
So how can you sleep better in hot weather?
Air conditioning is one answer, but it’s not affordable or practical for many households. According to the Energy Saving Trust, the cost of electricity under the price cap from July to September 2026 will be 26.11p per kWh for direct debit customers. A small portable air conditioning unit used for 30 nights, 7 hours a night, using around 1kW, would cost you around £54.83 in electricity alone before you bought it.
Research on residential overheating shows that shading and ventilation may be important passive cooling strategies. This means reducing indoor heat without mechanical cooling. It helps reduce heat entering your home before cooling the air. Overheating is usually caused by sunlight entering through windows and warm outside air, known as solar gain.
These eight steps will help keep your bedroom cool before nightfall.
1. Avoid sunlight during the day
On sunny days, close curtains or blinds on windows facing the sun. This reduces sunlight entering the room and heats the floors, walls, and furniture. External shading, such as shutters, awnings, and awnings, are even more effective because they block some of the sunlight before it reaches the glass.
Be careful with windows. If the air outside is hotter than the air inside, opening windows can allow heat to enter the room. Open your windows when the air outside is cooler than inside, often in the early morning, evening, or night. If it’s warm outside, close them during the hottest part of the day.
2. Use cross ventilation when the outside air is cool.
Cross ventilation means opening windows and doors on different sides of your home to allow air to flow through. Cooler outdoor air helps remove heat built up indoors. Research on passive cooling in homes has shown that nighttime ventilation can reduce overheating, but its effectiveness varies depending on the building, outdoor temperature, safety, noise, and air quality.
3. Reduce heat from conservatories and sun-facing rooms.
Conservatories can get very hot as sunlight passes through the glass and warms the internal surfaces. Maintain ventilation during the day and, if possible, close internal doors between the conservatory and the rest of the house. Reflective films, blinds, shutters, awnings and shaded roofs can all reduce heat gain.
Loft spaces and rooms on top floors can also get hot because the roof absorbs the sun’s heat. Loft ventilation and reflective roofing may help, but are usually more substantial interventions. For example, rooftop solar panels can generate electricity while acting as a barrier to reduce heat transfer to the building.
4. Move where you sleep
If your bedroom is on an upper floor or faces south or west, it may be one of the hottest rooms in your home. Heat rises into buildings, and sun-facing walls and roofs can continue to release the stored heat even after sunset.
During a heatwave, sleeping on the ground floor or north side of your home may help.
5. Reduce indoor heat and humidity
Ovens, stoves, tumble dryers, washing machines, and dishwashers can all heat indoor spaces. Cooking and drying clothes indoors increases humidity, making it harder for sweat to evaporate.
On very hot days, use heat-producing appliances early in the day or late in the evening. When you cook or take a shower, use an exhaust fan to allow warm, moist air to spread throughout your home. Studies on moisture transfer and ventilation fans have shown that fans can reduce moisture transfer from kitchens and bathrooms to other rooms.
6. Choose breathable bedding and clothing
A review of fiber types in sleepwear and bedding found that bedding and clothing can impact thermal comfort during sleep. Light, loose-fitting sleepwear and bedding help dissipate body heat. Cotton and linen are often more comfortable because they absorb moisture and allow air to pass through, but the weave, thickness, and moisture handling of the fabric are also important. Avoid heavy bedding, thick duvets, and tight synthetic fabrics that trap heat and moisture.
7. Use fans carefully
Evidence regarding the use of electric fans in hot climates suggests that they are useful in many hot situations, but their safety depends on temperature, humidity, age, hydration, and health status.
Fans do not cool the air. By moving air across your skin, it accelerates sweat evaporation and helps you feel cooler.
In cases of very high temperatures, a fan alone may not be enough, especially for elderly people and people who are dehydrated or unwell. If you use a fan, drink water, avoid keeping the fan on your face while sleeping, and stop using it if you feel hot, dizzy, or unwell.
8. Safely try low-cost cooling aids
Some people find comfort in using reusable ice packs, freezing blocks, and cooling pillows. Wrap the ice pack in a cloth or place it on a tray to prevent condensation from soaking your bedding or letting cold air come into direct contact with your skin.
Cooling mattress toppers and bedding using water or phase change materials may also be helpful. These materials absorb, store, and release heat during changing conditions, although their costs and effectiveness vary.
In hot weather, your sleep will improve long before bedtime.
The most effective approach is usually a combination of: Block sunlight during the day, ventilate when it’s cool outside, reduce heat from appliances, sleep in the coolest room available, and use bedding that wicks body heat away.
