How to get a good night’s sleep in the heat: Our experts reveal exactly why the hot weather is making you constantly tired, lethargic and irritable, why women have it worse… and the surprising mistakes you are making

Are you feeling tired, lethargic, and possibly more irritable?

The long, sticky nights of our endless heatwaves – we’re now enduring our fifth – could be to blame, playing havoc with our sleep.

New research by One Poll found that 48 per cent of UK adults regularly lose sleep because they’re too hot at night.

And a YouGov poll of 2,135 people found two in three people in the UK struggled to sleep during June’s heatwave, with almost half saying they lost at least three hours’ sleep a night.

Not only do we feel weary the next day, but this has been going on for weeks on end, affecting important parts of our sleep cycle and our ability to think clearly and control our emotions.

So why don’t we sleep properly in the heat, and what can we do to minimise the impact?

‘When we’re too warm, our body struggles to lower its core temperature, which is an essential part of the process of falling asleep and staying asleep,’ explains Maja Schaedel, a clinical psychologist and director of the Good Sleep Clinic in Kent.

‘The ideal bedroom temperature is typically between 16C and 18C, so warm summer nights can make it much harder to achieve restorative sleep.’

Women can be particularly vulnerable because hormonal fluctuations can influence body temperature regulation, Russell Foster, a professor of circadian neuroscience at the University of Oxford, told the Daily Mail.

‘For instance, before ovulation body temperature rises, and for menopausal women, there’s the added factor of hot flushes – which can cause a further rise in core temperature due to fluctuating hormones making the sufferer feel even warmer,’ he explains.

Even if you do manage to drop off, the high temperature can often mean you wake up during the night.

‘That’s because the drop in core body temperature, though needed to trigger sleep, won’t guarantee restorative deep wave sleep [because of the high temperature in the night],’ adds Professor Foster

Maja Schaedel explains: ‘When it is hot, our body must work harder to keep us cool. This means a faster heart rate to pump oxygenated blood around our body and our breathing quickens. These symptoms mimic symptoms of alertness and make it hard for the brain to interpret that you are safe and to go back to sleep.’

All of which means we can miss out on deep, restorative sleep and feel tired the next day.

Though even if you sleep well, you can feel tired. ‘The mechanisms needed to cool down the body also require energy and energy generates heat,’ says Professor Foster, ‘which is why you feel more exhausted when you are hot. You can have a good night and still feel exhausted because of demands on the body.’

‘Another theory is that, in the same way when we’re ill, there are neurons [brain cells] that induce changes that cause fatigue, they may potentially follow the same neural pathway and make us feel tired when it’s hot,’ says Guy Leschziner, a consultant neurologist and professor of neurology and sleep medicine based in London.

‘During a heatwave our sleep may also be more fragmented than usual which means we are more likely to wake up early’ explains Lindsay Browning, a neuroscientist at the Trouble Sleeping clinic in Berkshire.

If the cycle of heatwaves continues, the repeated disturbed sleep will have an impact on our health and wellbeing.

‘In the short term it will impair emotional and cognitive responses so you should avoid, say, making serious decisions.’ says Professor Foster. ‘It can also lower your immunity as lack of sleep increases the stress response and high levels of the stress hormone cortisol suppresses the immune system.’

Part of the problem, of course, is that our homes simply aren’t suited to extreme heat. A study last year by Loughborough University found that one in five homes were not equipped to deal with hot weather because of factors such as inadequate shading and poor ventilation.

So what pre-emptive steps can you take to minimise the impact of the heatwave on your sleep?

Prevention is better than cure

Yes, you might have heard it before, but it really is important to keep the windows shut during the day (with the curtains closed or blinds down) to trap cooler air inside and keep it circulating, Chris Sansom, a professor of solar power at the University of Derby, told the Daily Mail.

‘You can also place a fan facing an open window to help push warm air outside,’ he adds.

Professor Foster suggests waiting until the temperature has dropped below 20C (68F) before opening windows in the evening and open the front and back windows or doors to get an air flow through the house.

Taking a tepid bath or shower before going to sleep can help, too.

‘The theory is that the warmth causes the blood vessels near the surface of the skin to dilate, increasing blood flow to the skin,’ says Professor Leschziner.

‘This allows the body to release heat more efficiently, helping to bring down its core temperature afterwards.

‘A cold shower may seem like the obvious solution, but it causes the blood vessels to constrict, which can temporarily reduce heat loss through the skin.’

In terms of bedding, Dr Hana Patel, a GP at online retailer Time4Sleep, recommends putting sheets in a plastic bag in the freezer for a short time before going to bed – not to lower core body temperature but simply so the bed feels cooler.

‘It should only take around half an hour in the freezer for your sheets to reach a comfortable cool temperature as you want to be sure you don’t actually freeze them!’

In the same vein, Dr Browning suggests using a hot water bottle filled with crushed ice and cold water to cool you and the bed

She adds: ‘Plus you could spray yourself with cool water from a misting water bottle.’

You could also try the Scandinavian sleep method, where you and your partner each use your own lightweight sheet or duvet, says Ilona Andrews, a sleep consultant and founder of organic babywear company, Sleeping Stars suggests. ‘Sharing covers creates one pocket of trapped body heat, whereas separate ones let you control your own temperature.’

If the heat wakes you up

Maja Schaedel says if she wakes up in the night feeling hot, she uses a flannel soaked in warm water and wipes it all over the skin.

‘Warm water brings the heat to the surface of the skin, helping it to evaporate quickly and enabling your body to cool down very quickly.’

She adds: ‘Avoid spending long periods of time in bed awake tossing and turning. Instead go and read a book for a bit, walk on cool tiles, go downstairs (heat travels upwards so downstairs is usually cooler), then head back to bed when you’re feeling a bit sleepier and cooler.’

GP Dr Roger Henderson adds that if you stay in bed it is important to keep the room dark – perhaps using an eye mask to avoid early morning light.

‘And resist the temptation to start scrolling on your phone since bright light and visual stimulation are likely to make it much harder to get back to sleep.’

How to beat the next day tiredness

If your broken nights are limited to the heatwave then trying to catch up on sleep will help combat crashing daytime tiredness. Normally we’re told to stick to a routine of going to bed and getting up at the same time each day – but a heatwave may be the exception.

‘If you can lie in bed a bit longer in the morning or at the weekend then do so – just to get that extra sleep,’ says Professor Leschziner. ‘I wouldn’t recommend this long term because it can disrupt sleep but it’s reasonable for a few days.’

As for napping, Professor Leschziner points out that too many naps can be counterproductive, as they may disrupt the body clock.

‘Ideally, you want to time a nap around the natural dip in our circadian rhythm, which tends to occur in the early afternoon, after lunch. Keep naps short – around 20 to 30 minutes – as longer periods of sleep can leave you feeling groggy and may make it harder to sleep at night.’

Professor Foster advises keeping cool by using a fan with ice cubes in front of it – ‘for this very reason I bought a small ice machine– so have an endless supply of cubes’.

‘Fan cough’ is real and here’s how to beat it 

It’s tempting to sleep with a fan on all night to try to stay cool, the downside is ‘fan cough’.

‘Having a fan blowing directly into your face may dry out the mucous membranes lining your nose, mouth, and throat,’ explains Dr Edward Nash, a consultant respiratory physician at George Eliot Hospital in Warwickshire.

These tissues, which aren’t meant to remain dry, can then become irritated. In response, your body may try to compensate by producing extra mucus, which can make symptoms worse as the excess secretions may run down the back of the nose and throat, causing throat irritation and coughing.

Part of the problem may be the fan itself, adds Dr Anindo Banerjee, a consultant respiratory surgeon at Southampton General Hospital.

‘If you dust your house every week, you should also dust the fan blades – otherwise it’s blowing dust at you,’ he says. ‘Dust can be very irritating to the delicate lining of the airways, so the body responds by trying to get rid of the particles. One of the easiest ways to do this is through coughing.’

Another issue is if you use a fan without any form of humidification – something that adds moisture to the air – as the fan draws moisture away from the surface lining of the nose and throat (this is why we also cough on planes and in air conditioning).

Dr Banerjee suggests placing a bowl of cool water in front of or underneath a fan to add moisture to the air.

‘And above all, remember that the fan doesn’t need to be blowing directly into your face. It cools you simply by moving air over your skin, which helps your body release heat. For a more comfortable experience, point the fan towards your body instead.’