When the weather heats up it can be hard to sleep.

sleeping in the heatHot summer nights. Tossing, turning, finding it hard to get to sleep or stay asleep because of the heat. Many people find sleeping in the heat difficult, particularly those who already find sleep challenging. Many people I see with sleep disorders such as insomnia, sleep apnea or narcolepsy dread the summer and heat as it makes sleep much more difficult for them. Although we can’t change the weather, and are likely to face more hot weather in the future, there are things that can be done to make sleeping in the heat easier to manage.

Why is it hard to sleep in the heat?

Apart from the obvious discomfort of feeling hot and uncomfortable, there are sound reasons why people don’t sleep their best during hot weather. An important part of dropping off to sleep is a drop in core body temperature. The body achieves this by diverting blood to the periphery (hands and feet) and surface (skin). If these parts of the body are in contact with air that is cooler than 37 degrees Celsius (98 F) heat is dissipated and the core body temperature drops enabling sleep. Throughout sleep, the body aims to maintain a core body temperature slightly lower than waking temperatures, so continues to use the hands, feet and skin to dissipate heat. This is one of the reasons people can feel better sleeping in the heat with their feet and legs hanging out from under the covers. It’s also why moving air, such as from a fan can help with sleep as the moving air enables greater heat exchange between the skin and air.

There is a lot of variation in preferred sleeping temperature, with people having a wide range of preferred temperatures. However, people seem to sleep best when bedroom temperatures are between 16-24 degrees Celsius (61-75 F). Those who are used to sleeping in warmer temperatures such as when living in the tropics can acclimatise to a certain degree and sleep reasonably in bedroom temperatures up to 28 degrees Celsius (82 F).

What can be done to help sleeping in the heat?

There are a number of things that can be done to improve sleeping in the heat. Those who are fortunate enough to have air conditioning may not need to be as careful of these factors as they are able to control the temperature in their bedroom environment, keeping it within a comfortable range. Other things that can help are:

  • Recognise that it’s only temporary: For most people in south eastern Australia, particularly Melbourne, heat waves only last a few days. So, although it may be hard to sleep on some nights, the weather will usually break after a day or two allowing a chance to catch up.
  • Don’t talk yourself out of sleeping: People who have trouble sleeping can be very sensitive to threats to sleep, like a particularly hot night. The anticipatory anxiety about the heat making it even harder to sleep, can make things worse than they would be otherwise.
  • Embrace napping: During heatwaves when sleep can be harder at night, for some people napping is a strategy they can use. Catching up on lost sleep during the day can reduce the impact it has on energy levels and concentration.
  • Bedding:  Bed-clothes are used most of the year to provide insulation and prevent excessive heat loss, particularly during REM sleep when the body does not as tightly regulate temperature. However, bedding can prevent heat loss via evaporative cooling, so during heat waves doing without bedding and sleeping either uncovered or under just a thin cotton sheet can help to reduce core body and skin temperature.
  • What to wear:  In the same way that bed clothes can reduce evaporative cooling, pyjamas or sleepwear can also keep heat in. Sleeping with skin exposed to moving air provides the greatest surface area for heat exchange and reducing body temperature.
  • sleeping in the heatMoving air / fans:  Air moving across the body is a very effective way of helping the body dissipate heat. This can be achieved with use of fans, either ceiling or electric fans, if there is no breeze. For many people, use of a fan during sleep is enough to help sleeping in the heat during all but the hottest nights.
  • Air conditioning:  Being able to cool air in the bedroom, with an air conditioner, in to a comfortable range for sleep is a great way to manage sleeping in the heat. But, not everyone has access to air conditioning, and air conditioning also reduces humidity so can increase other symptoms such as nasal congestion for some people.
  • Go somewhere else:  If sleep is vitally important to you or your health and you can’t manage your sleeping environment using air conditioning, consider going to stay with a friend or even book in to a hotel during extreme heatwaves. This is particularly important for those with medical conditions such as respiratory or heart problems who are at increased risk during heatwaves.

For a discussion on sleeping in the heat listen to this audio interview:

So don’t let a heatwave upset your sleep routine. Use these strategies to help with sleeping in the heat, and recognise that there are things that can be done to help reduce the impact of heat on your sleep.

Related posts & links:

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Showing 5 comments
  • Kaila

    I have trouble sleeping normally but the hot weather make me sleep, it knocks me out. It is like my way of dealing with the heat is to sleep through it. My mum could never understand it, not sure I do either. I have fainted in the past from being to hot.

    • Dr David Cunnington
      Dr David Cunnington

      Kaila, thanks for your comments. Although some people have trouble sleeping in the heat, others have the reaction you describe. When it gets hot, they can feel sleepier and sleep longer and deeper.

  • Photobooth Journal

    Great advice Dr C! Thank you.

  • Vicki

    No comment on the article (I’m lucky enough to have air conditioning in my bedroom) but I just want to thank you for your consistently informative and well-written articles, always well cross-linked! As someone who developed the curse that is insomnia over the past five years, I hope to consult you professionally this year!

    • Dr David Cunnington
      Dr David Cunnington

      Vicki, Thanks for the feedback.

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