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Healthy Sleep

5 min read

sleeping in the heat - how do heat waves impact sleep?

written by Liz Tabron

updated 12.07.2022

Woman can't sleep in the heat - stay cool in the heatwave

Hot summer days, you either love them or can’t stand the heat, but one thing heat waves bring for many of us is a restless and uncomfortable night’s sleep. During summer heat waves, high overnight temperatures can impair our sleep and are associated with a reduction in important sleep stages, leading to increased wakefulness and a poor night’s sleep, and so it’s no wonder you’re left feeling groggy and far from refreshed the next day. 

Read on to discover how high temperatures can have an impact on our sleep and how they can affect the body, plus we share some top tips on how you can sleep better during a heat wave.

how do high temperatures affect sleep?

Exposure to excessive and even mild temperatures can wreak havoc on your sleep, affecting your ability to fall and stay asleep and feel refreshed from sleep. Your body temperature follows a natural cycle during a 24 hour period - it drops in the evening, rises in the morning and peaks later in the day. 

When you go to bed, your body temperature continues to drop during the first two stages of your sleep cycle, and will reach its lowest point, maintaining this level for the rest of the night. Before you wake, your temperature slowly returns to its normal level, so you wake up feeling refreshed and alert ready to start the day.

During a heat wave, high temperatures during the night can interfere with the natural thermoregulation that takes place during sleep and if your bedroom is too hot, this can raise your body temperature, which in turn will have a negative impact on your sleep quality. 

We have two types of sleep, rapid eye movement (REM) and non rapid eye movement (NREM).  NREM is split into three stages - The first two NREM stages of sleep are when you are more sensitive to temperatures, meaning if you’re too warm, you’ll be more likely to wake up. Waking up during these two stages of sleep, can reduce the time spent in the third and deepest sleep stage - slow wave sleep, as well as REM sleep. Slow wave and rapid eye movement sleep are key to helping you feel rested each morning and if these sleep stages are disrupted, your body won’t recover as much throughout the night, and so you’ll feel tired and less refreshed.

A combination of sleep deprivation and high temperatures can also negatively impact cognitive performance, such as focus and attention. So it’s no surprise that we don’t feel or perform at our best when we don’t get enough sleep and when it’s way too hot. Furthermore, when you’re sleep deprived, you’re more likely to experience the symptoms of heat stress more acutely too.

how hot temperatures can affect your body

Excessive heat doesn’t just negatively impact your sleep quality, it can also affect your body in other ways too. Our bodies strive to maintain a core temperature of 37.5C, regardless of how hot or cold the weather is. When the weather gets hotter, your body has to work harder to keep its core temperature down and so more blood vessels open up near the skin in order to lose heat and start sweating. As the sweat evaporates, heat loss from the skin significantly increases. 

Hot summer weather raises the risk of heat stress, which is what happens when your body is unable to cool itself enough in order to maintain a healthy temperature. Lack of airflow, dehydration, sun exposure and hot, crowded conditions can all lead to heat stress. 

The body cools itself by sweating, but sometimes this isn’t enough and your body temperature can keep rising and that’s when heat-related illnesses can occur including heat exhaustion and heatstroke. 

Heat exhaustion - this happens when you start to lose water or salt from your body and symptoms include feeling faint and muscle cramps. 

Heatstroke - this occurs when your body reaches 40C or higher and the symptoms are similar to heat exhaustion, but you can lose consciousness, have dry skin and stop sweating, and so medical emergency care is needed.

Prevention is the best way to manage heat stress and there’s a number of things you can do to keep cool when the temperature starts to rise, including:

  • Drink plenty of water

  • Stay out of the sun as much as possible

  • Wear loose fitting clothing

  • Don’t overexert yourself

  • Keep energy levels up

  • Make use of fans and ice

  • Have cool showers

how to sleep better during a heat wave

When it’s too hot to sleep it’s all too easy to get stressed and feel restless, but don’t despair, there’s actually a few things that you can do to help your body maintain a lower temperature, helping to prevent heat stress and making sure you get the quality sleep you need.

  1. Keep your bedroom cool - A bedroom that’s cool and comfortable is key to a good night’s sleep, so during a heat wave, keeping sunlight out of the room by closing the curtains or blinds will go a long way to ensuring the space feels cooler. Blackout curtains are designed to block out all outside light, making them effective at keeping the bedroom cool on those hot summer days.

  2. Choose cooling bedding - The right bedding really can make a difference to how comfortable you feel throughout the night. Opt for bedding made from natural materials, such as cotton, as they provide better breathability compared to synthetic fabrics. To aid a blissful night’s sleep during a heat wave, the Silentnight Cool Touch range offers a refreshing place to rest.

  3. Keep a glass of ice water near your bed - It’s a good idea to keep a glass of ice water within easy reach of your bed, which will give you quick and much-needed relief if you wake up feeling too hot. 

  4. Place a cool pack on pulse points - Keep a cool pack in the freezer ready to grab and place on your pulse points when you’re really feeling the heat, this will help your entire body to cool down. 

  5. Freeze your pillowcases - For an extra cooling effect, place your pillowcases in the freezer in the evening and then put over your pillow before getting into bed.

  6. Keep calm and relaxed - Try to keep calm and relaxed if you’re struggling to sleep. Rather than lay there tossing and turning, get up and do something relaxing instead such as reading or listening to some soothing music and then return to bed once you feel sleepy.

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