If you are struggling to sleep through the UK heatwave, help is at hand.
With this year's May bank holiday breaking records - temperatures reaching as high as 32C in some parts of the country - it is no surprise that many of us are tossing and turning at night. Amber heat health alerts have been issued for the next two days across large parts of England, including London, the South East, the East of England, the West Midlands and the East Midlands.
Some tips for beating the heat during the day are well known: make use of shady spots, stay hydrated by drinking plenty of water and wear light, loose clothing. But what should we be doing when night falls and the discomfort often becomes even harder to escape?
Scientists have identified six key steps to achieving sounder sleep during hot weather, pinpointing what they call "sleep enemies" that come to the fore when temperatures rise.
According to a study published in the journal One Earth in 2022, people have been losing an average of 44 hours of sleep per year since 2000 compared to those from earlier centuries, with scientists attributing the trend directly to rising temperatures. Kelton Minor of the University of Copenhagen warned the problem is set to worsen significantly, predicting a potential loss of up to 58 hours of sleep per year by 2099, based on data gathered from 47,000 people across 68 countries.
A 2024 review in Sleep Medicine Reviews explained the mechanism: "In hot sleeping environments, heat production can exceed heat loss beyond tolerable levels, increasing core body temperature and disturbing the natural sleep-wake cycle with increased wakefulness." Researchers added: "The largest investigation of the effect of ambient temperature on sleep thus far found that increased nighttime ambient temperature shortens sleep duration, primarily through delayed sleep onset, with stronger negative effects during summer months."
According to The Sun, Armelle Rancillac, a neuroscientist at the Centre for Interdisciplinary Research in Biology, warned that chronic sleep deprivation is known to disrupt the body's ability to recover. The immediate consequences include exhaustion, difficulty concentrating and a significantly greater chance of accidents, whether behind the wheel or in the workplace. Sustained poor sleep builds into a harmful "debt" that touches almost every system in the body, disrupting how we process food, increasing susceptibility to conditions including diabetes, heart disease and weight gain, and potentially accelerating neurodegenerative illnesses such as Alzheimer's. A persistent sleep deficit can also erode resilience under stress and take a significant toll on mental health.
In the report, Fabien Sauvet, a researcher at Paris Cité University, said lowering the body's internal thermostat is the key to better sleep in warm conditions, but warned that adapting to heat comes at a physiological cost. "We sweat more and faster, for example, but it requires additional hydration," he explained. "And it has limits, so during heatwaves, the most important thing is to adapt our behaviour," including activities, schedules and clothing.
To sleep better in the heat, Dr Rancillac advised paying close attention to "sleep enemies" and taking the following steps instead.
If the heat is making sleep feel impossible, a cool shower before bed can help ease you into sleep more comfortably. Dr Rancillac recommends cool rather than cold, as scientists warn that forcing the body into very cold temperatures during a heatwave may trigger a response that causes it to retain heat, which is counterproductive.
Reaching for the air conditioning or a fan is an instinctive response to hot weather, but Dr Sauvet challenged what he called "the false belief that the bedroom must be at 18-20°C." He pointed to studies showing that good sleep quality is achievable at room temperatures of up to 28C, and argued that people can "tolerate higher temperatures than commonly thought." His advice: opt for light pyjamas such as a t-shirt and shorts, use a sheet rather than a duvet and make sure the room is well ventilated. "If we always sleep with air conditioning, we will never acclimatise," he said.
Caffeine is a stimulant and, however appealing a coffee might be after a restless night, it is likely to make the next one worse. Cutting back on consumption and staying well hydrated with water is a better strategy when sleep is already under pressure from the heat.
A cold drink in the evening sun may feel like the perfect way to unwind, but alcohol can interfere with sleep quality. The problem is that alcohol causes a modest but measurable rise in body temperature, meaning that even if it eases the initial transition into sleep, broken and restless nights are far more likely to follow. Limiting both alcohol and caffeine is advisable during a heatwave.
A warm bath is a reliable wind-down ritual for much of the year, but during a heatwave it can work against you. Dr Sauvet advises against hot baths or hot tubs when temperatures are already high. A cool bath or an evening walk outdoors are better alternatives for relaxing the body before sleep.
If the heat has already cost you a night's sleep, a short daytime nap can help offset the effects. Research cited by Dr Sauvet shows that resting during the peak heat of the day can meaningfully offset the effects of a disrupted night, but timing and length matter — half an hour is ample, and finishing well before 2pm ensures the nap does not eat into the following night's sleep.
