Struggling to sleep in the heat? The good news is that a handful of easy cooling tricks can help your body stay comfortable and make hot nights far more bearable.
When temperatures rise, sleep often suffers. Hot nights can make it harder to fall asleep, increase waking during the night, and leave people feeling less rested the next day.
One reason is thermoregulation, the body’s ability to keep its internal temperature within a safe range. Sleep is closely linked to body temperature: to fall asleep and stay asleep, the body usually needs to lose some heat. Hot bedrooms make that harder.
And UK summers are becoming hotter. The Met Office has reported that the chance of exceeding 40°C in the UK is now more than 20 times higher than it was in the 1960s, with a 50% chance of another 40°C day in the next 12 years.
Why Heat and Humidity Disrupt Sleep
Humidity can make the problem worse. Research on humidity and heat stress shows that high humidity can increase the strain heat places on the body. The body cools itself partly by sweating. As sweat evaporates from the skin, it carries heat away. But when the air is already humid, evaporation becomes less efficient.
So how can you sleep better in hot weather?
Air conditioning is one answer, but it is not affordable or practical for many households. According to the Energy Saving Trust, the electricity unit rate under the July to September 2026 price cap is 26.11p per kWh for direct debit customers. A small portable air-conditioning unit using about 1 kW for seven hours a night over 30 nights would cost around £54.83 in electricity alone, before buying the unit.
Research on overheating in homes shows that shading and ventilation can be important passive cooling strategies: reducing indoor heat without mechanical cooling. Before cooling the air, then, it helps to reduce the heat entering the home. Overheating usually comes from sunlight entering through windows, known as solar gain, and warm outside air.
These eight steps can help keep bedrooms cooler before nightfall.
1. Block Sunlight Before Your Bedroom Heats Up
On sunny days, keep curtains or blinds closed on sun-facing windows. This reduces sunlight entering the room and heating up floors, walls, and furniture. External shading, such as shutters, awnings, or shades, can be even more effective because it stops some sunlight before it reaches the glass.
Be careful with windows. If the air outside is hotter than the air inside, opening windows can bring heat in. Open windows when the outside air is cooler than indoors, often early in the morning, evening, or overnight. Close them during the hottest part of the day if the outside air is warmer.
2. Cool Your Home With Cross-Ventilation
Cross-ventilation means opening windows or doors on different sides of a home so air can flow through. When outdoor air is cooler, this can help remove heat that has built up indoors. Studies of passive cooling in homes have found that nighttime ventilation can reduce overheating, although effectiveness depends on the building, outdoor temperature, safety, noise, and air quality.
3. Prevent Heat Build-Up in Hot Rooms
Conservatories can become very hot because sunlight passes through the glass and warms the surfaces inside. Keep them ventilated during the day and, where 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 top-floor rooms can also become hot because roofs absorb solar heat. Loft ventilation or reflective roof materials may help in some homes, although these are usually more substantial interventions. For example, solar panels on the roof can generate electricity and at the same time act as a barrier to reduce heat transfer to the building.
4. Sleep in the Coolest Room Available
If your bedroom is on an upper floor or faces south or west, it may be one of the hottest rooms in the house. Heat rises through the building, and sun-facing walls and roofs can continue releasing stored heat after sunset.
During a heatwave, sleeping on the ground floor or north-facing side of the home may help.
5. Cut Indoor Heat and Humidity
Ovens, hobs, tumble dryers, washing machines, and dishwashers can all make indoor spaces warmer. Cooking and drying clothes indoors can also increase humidity, making it harder for sweat to evaporate.
On very hot days, use heat-producing appliances earlier in the day or later in the evening. Use extractor fans when cooking or showering because they remove warm, moist air before it spreads through the home. Research on moisture movement and extractor fans has shown that fans can reduce the movement of moisture from kitchens and bathrooms to other rooms.
6. Choose Bedding That Keeps You Cool
A review of sleepwear and bedding fiber types found that bedding and clothing can affect thermal comfort during sleep. Light, loose sleepwear and bedding can help the body lose heat. Cotton and linen are often comfortable because they absorb moisture and allow air movement, although fabric weave, thickness, and moisture handling also matter. Avoid heavy bedding, thick duvets, and tight synthetic fabrics that trap heat and moisture.
7. Use Fans the Right Way
Evidence on electric fan use in hot weather suggests that fans can be useful in many hot conditions, but their safety depends on temperature, humidity, age, hydration, and health.
Fans do not cool the air. They move air across the skin, which can help sweat evaporate and make people feel cooler.
In very high temperatures, especially for older adults or people who are dehydrated or unwell, fans alone may not be enough. If using a fan, drink water, avoid directing it continuously at the face while sleeping, and stop using it if it makes you feel hotter, dizzy, or unwell.
8. Try Simple Low-Cost Cooling Solutions
Reusable ice packs, freezer blocks, or cooling pillows may help some people feel more comfortable. Wrap ice packs in a cloth or place them on a tray to avoid condensation soaking bedding or direct cold contact with skin.
Cooling mattress toppers and bedding that use water or phase change materials may also help. These materials absorb, store, and release heat as they change state, although cost and effectiveness vary.
In hot weather, better sleep starts long before bedtime.
The most effective approach is usually a combination: block sunlight during the day, ventilate when outside air is cooler, reduce heat from appliances, sleep in the coolest room available, and use bedding that allows the body to lose heat.
Amin Al-Habaibeh receives funding from Innovate UK, the British Council, the Royal Academy of Engineering, EPSRC, AHRC, the British Academy, the Royal Society, and the European Commission. He is also a member of The Institution of Engineering and Technology (The IET).
Dr. Luke Siena has received funding from Innovate UK and the National Institute for Health & Care Research (NIHR). He is also a member of The Institution of Engineering Designers (IED), a member of The Institution of Engineering and Technology (IET), a member of The Institute of Materials, Minerals & Mining (MIMMM), and is an Affiliate Fellow of the Chartered Society of Designers (CSD).
Adapted from an article originally published in The Conversation.
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1 Comment
For people who don’t have much money, believe it or not, filling a pool float mattress with about an inch or less of water, and putting it underneath the sheets (2 of them for a full or queen bed) will help tremendously. It’s not even necessary to fill with ice water, although an ice pad like is used for sports injuries on the corners or the middle for an hour before getting into bed won’t hurt. Those mattresses are very inexpensive, so some may even feel they can buy new each year. I’ve never tried to empty one and use it for air after using it for water. The water conducts heat so you at least feel cooler and if you do ice the corners you can adjust to your preference even if the house is very hot. Just don’t go overboard on it.