You go to bed feeling fine and comfortable, throughout the night, you toss and turn in and out of sleep while getting hotter, or you wake up in the middle of the night hot and sweaty. You’re not alone. With more awareness about sleep quality, many are asking “why do I get hot when I sleep?”
First, it’s important to know that our core body temperature drops during rest, and that our bodies regulate this lower temperature for a full night’s sleep. The body cools itself by releasing heat. It does this by increasing blood flow to the surface of the skin, so body heat is released into the air. If our environment makes it hard for our bodies to release that heat, we end up feeling uncomfortable.1
The temperature of both your body and your surroundings can affect your quality of sleep, so let’s look at both these factors.
Your body needs cooler temperatures to sleep well2, so if your room is getting hotter at night, this can wake you from your rest. Our bodies release radiating heat. The ideal temperature for rest is 18 degrees Celsius, so your core body temperature when resting can be stable and uninterrupted. Check how hot your bedroom is during the day, and whether the bedroom is getting hotter at night. There may be electronic devices that can generate heat in a closed room, or perhaps shut windows mean the air can’t circulate.
More bedding and sleepwear are made with synthetic materials and fabrics, such as memory foam, polyester or nylon, and some can even be mixed into blends with cotton or linen. These synthetics and blends may be helpful in Winter, but they also cause you to overheat. These materials, including silk, may retain heat and do not allow your skin to breathe, making it difficult for your body to regulate your core temperature throughout the night.
Most of us are trying to stay fit when we can, and that can mean exercising after work and other commitments. While exercise on its own is positive for overall health, the timing and type of exercise may be contributing to you feeling uncomfortably hot in the middle of the night. In general, exercise earlier in the day can help stabilize your Circadian rhythms which helps for a full night’s rest. And opting for gentle exercise at night can decrease sleep interruptions.3
Fast food, snacks and takeaway can be a helpful way to save time when busy or after a long day, but it may also be a factor in why you’re sleeping hot and bothered. Sleep interruptions may decrease with a healthy balanced diet, with some foods helping us sleep.4 And research suggests that the better we sleep, the better our bodies can digest and absorb nutrients, too. So, diet health and sleep health is connected.5
The tensions that we bring to our bedrooms can affect our sleep. Working late, checking your phone, ruminating, reading or watching the news before bed can bring a spike in stress. These actions are more consistent with waking life than preparing for bed. If your body rhythms get confused by these inconsistent patterns of concentration, you may find yourself waking up hot and stressed in the middle of the night. Settling into a stable sleep routine that avoids any stressful content or activities will help to improve your sleep.
There may be other reasons that are causing you to wake up feeling hot. It’s important to consult your doctor if you feel like there are certain conditions or medicine you take that might be contributing to your hot nights and interrupted sleep.
The good news is that now you know some of the reasons you sleep hot, and why it’s important to stay cool, you can also make some easy changes to help your sleep quality. Here are a few practical ways you can beat the heat, stay cool and sleep well through the night.
Getting your bedroom ready for a cool night’s rest starts with keeping it cool during the day. In hotter months, keep the room closed so the outside heat doesn’t get in, and keep it dark with curtains or blinds so it doesn’t get heated up by the sun. Unplugging all electronic devices can also reduce the heat being generated3, and make it a cooler sanctuary for your nighttime routine.
If it’s cooler outside in the evening, leaving open your windows a crack can help you get some fresh air and keep the ideal temperature for a restful sleep throughout the night.
Natural fabrics such as linen, cotton and wool are all breathable fabrics to let your skin breathe and your body to cool itself. From your sleep wear to your bed sheets to the comforter or pillow you use – you might want to consider natural materials that are better able to help you cool down and regulate your core temperature during sleep4.
Investing in either a humidifier if you’re in a humid climate or a fan can help keep you cooler at night. A dehumidifier removes extra moisture from your room, helping to avoid that “hot and sticky” feeling that can interrupt your sleep. A fan will circulate cool air from outside or create a cooling affect by evaporating sweat when air is blown onto your skin. For some, the “white noise” of a fan can also be soothing aid for a restful sleep.
If you’re co-sleeping or with a partner, sharing a quilt, comforter or sheet can double the amount of radiant heat, increasing your body temperature throughout the night. Having separate bedding when you share a bed can help for you to regulate your own body temperature.
It sounds counter-intuitive, but a warm shower or bath can actually help you feel cooler as it encourages your body to start cooling its core temperature. Your body will start the process of vasodilation, where it increased the blood flow closer to the surface of our skin to drop your core temperature that’s best for sleep1.
A simple and low-tech way for those who sleep hot to cool down is with the help of your freezer. You can freeze your sleepwear or bedsheets, add chilled water or ice into an “hot water bottle” or use sports ice packs wrapped in a towel to chill your bed.
Taking time out to de-stress or unwind with a set routine before sleep preps your mind and body for a good night’s rest. Having a separation from your day when you’re getting ready for sleep will help to define a clear pattern and space for your mind and body to rest for the full night. Think of meditation to settle the mind, warm showers to kick-start your drop in core body temperature, wearing designated sleep wear and only using the bed for sleep.
Whether it’s a small change or a big switch for your sleep, we hope this helps you stay informed so you can feel fully rested. If you’re interested in checking your sleep quality, our personalized Online Sleep Assessment can give you some insight into about your sleep quality.
…some insight into what rest is best for you.
ResMed is a global leader in sleep technology that has its origins right here in Australia. Our goal is to provide people with the means to awaken their best and enjoy healthier lives by promoting good sleep habits and creating awareness for sleep disorders such as sleep apnea.
Neilson, S. (2019) A warm bedtime bath can help you cool down and sleep better, NPR. Available at: https://www.npr.org/sections/health-shots/2019/07/25/745010965/a-warm-bedtime-bath-can-help-you-cool-down-and-sleep-better (Accessed: 12 January 2024).
Why do I get so hot when I sleep? (2023) Sleep Foundation. Available at: https://www.sleepfoundation.org/sleep-faqs/why-do-i-get-so-hot-when-i-sleep (Accessed: 12 January 2024).
The best temperature for sleep: Advice & tips (2023) Sleep Foundation. Available at: https://www.sleepfoundation.org/bedroom-environment/best-temperature-for-sleep (Accessed: 12 January 2024).
Chow, Chin Moi, et al. “The Impact of Sleepwear Fiber Type on Sleep Quality under Warm Ambient Conditions.” Nature and Science of Sleep, vol. 11, 26 Aug. 2019, pp. 167–178, www.ncbi.nlm.nih.gov/pmc/articles/PMC6716586/, https://doi.org/10.2147/NSS.S209116.
Schofield, C. (2022, July 19). Simple hot water bottle hack can help you sleep during the heatwave. Yorkshire Evening Post. https://www.yorkshireeveningpost.co.uk/read-this/simple-hot-water-bottle-hack-can-help-you-sleep-during-the-heatwave-3773726
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