How to Sleep in a Heatwave: UK NHS Tips for Summer 2026
⚡ QUICK ANSWER
Cool the bedroom all day by closing sun-facing curtains from late morning and opening shaded-side windows. Have a lukewarm shower before bed, aim a fan across a bowl of ice or a frozen water bottle, and drape a damp flannel on your wrists. Dim the lights an hour before sleep. If anyone becomes confused, stops sweating or hits 40C, call 999—that is heatstroke.
On 26 May, temperatures rose to 35C, the UK’s highest May reading, prompting an Amber Heat Health Alert from the UK Health Security Agency (UKHSA) across swathes of England.
Running from Tuesday 26 to Thursday 28 May, a broader yellow alert had also been issued for the South on Friday 22.
If you inhabit a terraced house or a first-floor flat with no air conditioning, you will likely be unsurprised by this news. You will have spent the night sweating under cotton sheets wondering why the breeze simply evaporated around midnight.
You are not the only one—only 5% of UK homes own any type of air conditioner. The rest of us put our faith in open windows and positive thoughts, neither of which is useful when the lowest temperature overnight was still 22C.
This guide collates advice from NHS Beat the Heat, the UKHSA, the Sleep Charity and the British Red Cross into a tiered plan, from morning to 3 am when you wake up in a drenched, desperate panic.
Why sleep falls apart in a heatwave
THE CORE TEMPERATURE RULE
Your body needs to drop its core temperature by 0.5 to 1C to fall asleep. Above about 24C in the bedroom that drop becomes much harder—which is why a heatwave wrecks sleep latency, deep sleep and REM all at once.
Your body needs to lower its core temperature by about 0.5–1C to be able to fall asleep. It accomplishes this by moving blood towards the skin’s surface—primarily your hands, feet and face—so that heat can escape into the room.
The Sleep Charity, one of the UK’s foremost authorities on sleep education, advises a bedroom temperature of 16–18C for best sleep. The issue is straightforward: in a heatwave, a bedroom can fail to dip below 24C at any time, far less before you tuck into bed.
When that core-temperature dip cannot happen, your sleep latency—the length of time it takes to drift off to sleep—will increase. Once you do fall asleep, heat can eat into both the deep sleep and REM stages that perform the majority of physical recovery and memory consolidation. You wake up feeling like you have not slept much at all, because you have not, in any meaningful way.
There is also a circadian disruption: bright light in the early morning of summer pours through your window, forcing an advance release of cortisol and yanking you awake earlier than you want to be—or indeed need to be—until your alarm. In plain terms, the heat makes it harder for you to get to sleep, and the light makes it harder to stay asleep.
Much of the housing stock of Britain was built with cold winters in mind, not scorching summers. Terraced houses and loft conversions are adept at trapping heat. Brick walls store energy all day long and release it slowly over the course of the night—the exact opposite of what you need for sleeping.
What the NHS and UKHSA actually say
OFFICIAL UK ADVICE
- NHS Beat the Heat — close sun-facing curtains and windows by day, open them at night when it is cooler outside.
- UKHSA Adverse Weather and Health Plan — identify a cool room (ideally north-facing) for sleep.
- British Red Cross — have a lukewarm shower before bed and keep a glass of water by the side.
NHS Beat the Heat is much more specific than many imagine. The advice is not simply “keep cool.” Instead, it advises: “Keep your bedroom as cool as possible by closing curtains and windows that face the sun during the day and then opening windows when the outside temperature drops below the indoor temperature.”
That latter point is vital—on a 35C day, throwing open every single window at 2 pm is merely allowing hot air into the building.
The UKHSA’s Adverse Weather and Health Plan offers more specific direction. It recommends that people find one room within their house to keep cool—preferably one that faces north—and sleep there during a heatwave. If your bedroom lies baking under a south-facing roof all day, consider sleeping in another, lower room for the hot nights.
The UKHSA’s Heat-Health Alert system officially runs from 1 June to 30 September each year, but the Amber Alert issued on 26 May shows the season arriving earlier than expected. Key priority groups are the elderly (over 65s), babies, toddlers and those with long-term conditions. If you have friends in those categories, the advice is simple: check on them.
The British Red Cross highlights a practical point that trips many people up. It recommends having a lukewarm shower before you go to sleep, as this will help to lower your core temperature. Having a cold shower, however, has the inverse effect: your body contracts the blood vessels at your skin surface in an effort to preserve heat in your core. Minutes later, you feel hotter than you did beforehand. Lukewarm, not cold.
A tiered plan — morning, evening and in bed
Your night-time sleep is won or lost in the middle of the afternoon. The plan below is broken into four tiers, each targeting a different part of the day and night.
TIER 1 — DURING THE DAY
Close sun-facing curtains and windows from late morning. Open shaded-side windows if cooler outside. Hang a damp towel over a clothes airer for evaporative cooling. Swap to a 4.5 tog summer duvet or cotton sheet. Freeze a 1.5L water bottle for later use in bed.
TIER 2 — THE HOUR BEFORE BED
Have a lukewarm shower—not cold. Place room-temperature water by the bed. Avoid alcohol, big meals and intense exercise. Cut caffeine after 2 pm. Dim the lights one hour before your planned sleep time to support natural melatonin release.
TIER 3 — IN BED
Use a cotton sheet only—or none at all. Wear cotton nightwear or sleep naked. Aim a fan across a bowl of ice or the frozen water bottle. Place a damp flannel on wrists or feet. Adopt the starfish position for maximum heat radiation. Sleep alone if possible.
TIER 4 — WHEN YOU WAKE AT 3 AM
Drape a damp flannel on the back of your neck or wrists. Sip room-temperature water—not cold, which can trigger a sweating response. If still awake after ten minutes, move to the coolest room in the house. The downstairs hallway or kitchen floor is often significantly cooler than the upstairs bedroom.
Who needs extra care on a hot night
The UKHSA’s Adverse Weather and Health Plan lists several groups requiring extra caution. People over 65 living alone are high on the list—their bodies are less efficient at regulating temperature and many occupy older houses that are effective at trapping heat. Make a point of checking on them, especially during an official Heat-Health Alert.
Babies and young children need specific attention. Dress them in only a short-sleeved cotton vest—no sleepsuit, no blankets, no duvet. Aim for a room temperature of 16–20C and use a room thermometer to check it. Never position a fan to blow directly onto a baby.
Certain medications disrupt the body’s ability to shed heat: drugs used to treat high blood pressure (diuretics, beta-blockers), depression and psychosis can affect sweating, blood flow or fluid levels in the body. If you take any of these, you must be mindful of staying hydrated and cool.
Women who are pregnant already face an increased cardiovascular burden in hot weather, compounding the stress of heat on their bodies. Those with COPD, heart failure, diabetes or dementia should be regularly monitored—heat places an immense strain on every bodily system. The UKHSA’s advice is direct: these groups face the greatest risk during prolonged periods of hot nights.
When heat becomes a 999 call
999 ALERT
Call 999 if a person is confused, hot but NOT sweating, unconscious, seizing, very fast breathing, or has a body temperature above 40C. That is heatstroke—a medical emergency, not just heat exhaustion.
Heat exhaustion is a fairly common condition and is manageable. Symptoms include tiredness, dizziness, headaches, nausea, excessive sweating, muscle cramps and extreme thirst. If someone exhibits these symptoms, move them to a cool place, lie them down with their feet slightly elevated, and cool them with damp cloths while letting them sip small quantities of water for up to half an hour. According to the NHS, they should begin to feel better within 30 minutes.
If symptoms fail to improve—or if the person develops confusion, skin that has stopped sweating, a body temperature above 40C, loss of consciousness, seizures or rapid breathing—it is heatstroke. In such circumstances, do not wait. Call 999 immediately. The NHS guidance for heatstroke is unequivocal: this is a life-threatening medical emergency requiring prompt treatment.
Common heatwave-sleep myths
Plenty of folk wisdom circulates every time the UK heats up. Some of it is harmless; some of it is actively counterproductive. Here are four of the most persistent myths, and what the evidence actually says.
| Myth | Fact |
|---|---|
| Cold showers before bed cool you down. | A lukewarm shower works better—cold triggers vasoconstriction, trapping heat in your core. |
| Fans always help in heat. | UKHSA: fans are useful below 35C but can hasten dehydration above that point. |
| Drinking lots of cold water before bed prevents night sweats. | It just wakes you up to use the loo. Sip steadily through the evening instead. |
| Sleeping on the floor is always cooler. | Cooler, yes—heat rises. But check for dust and pollen during hay-fever season. |
Frequently asked questions
What is the optimal temperature for a bedroom during a heatwave?
According to the Sleep Charity, the ideal temperature range is between 16 and 18C. This may feel virtually impossible in a UK heatwave—and often, it is. What you are aiming for is to get as close as possible to this range using a combination of the daytime cooling techniques discussed above and the fan-with-ice method. Even dropping from 28C to 24C can make a tangible difference to the quality of your sleep.
Is it safe to leave a fan on all night during a UK heatwave?
Yes, as long as the ambient room temperature remains below around 35C. The UKHSA recommends that fans are effective at temperatures below this mark. Ensure you position the fan so that it does not blow directly onto your face, as this could dry out your airways and disturb your sleep. Aim it across a bowl of ice for extra cooling.
Can I take a cold shower before bed to cool myself?
No—and this is one of the most counterproductive things you can do. Cold water causes the blood vessels on your skin to contract, locking warmth inside your core. Warm water, on the other hand, helps open the pores and releases heat through evaporation. Use warm water.
How can I keep a baby cool overnight during a heatwave?
Dress the baby in only a short-sleeved cotton vest. Ensure the cot is free from all blankets, duvets and pillows. Try to keep the room temperature between 16 and 20C and verify this with a thermometer. You can use a fan to circulate air, but it should never blow directly onto the baby. Never put a baby in front of an open window or into a direct draft.
What are the NHS guidelines for elderly people sleeping during a heatwave?
NHS Beat the Heat advises that people aged over 65 should stay in the coolest available room, regularly drink water and avoid going outdoors during the hottest part of the day. At night, the UKHSA suggests checking on elderly neighbours and relatives—especially those who live alone. Seek medical help immediately if they display signs of confusion, dizziness or stop sweating.
Final thoughts
While you cannot control the weather, you can control the level of preparedness your bedroom is in before you occupy it. Cool the room during the day: close sun-facing curtains and windows from late morning onwards and open those on the shady side first thing. Take a lukewarm shower an hour before you go to sleep, sleep under a single cotton sheet, aim a fan across a bowl of ice or a frozen water bottle, and drape a damp flannel across your wrists. Dim your lights to give melatonin a decent chance to do its job.
If you know anyone over the age of 65 living alone, knock on their door. And if anyone starts behaving confusedly, stops sweating or registers a temperature above 40C, call 999—the NHS guidance is clear on this point. For a deeper look at recognising the difference, read our guide to heat exhaustion vs heatstroke NHS first aid. If you are a runner training through the heat, our article on exercise hyponatremia for UK runners in a heatwave covers the hydration risks you need to know.
The hot weather will not last. Tonight, stack the cards in your favour.
