Ever pushed the covers off you as you slept, only to grab them again in the middle of the night? Most of us struggle to achieve the best temperature for sleeping – we're usually either too cold or too hot. But what is the optimal temperature for a good night's sleep anyway? And why does temperature affect sleep so much anyway?
We've asked two leading sleep experts to explain everything you need to know about the ideal room temperature for sleeping, and why it's worth following.
Of course other factors can affect your sleep too, such as noise, too much caffeine, and too little or too much exercise close to bedtime. But if you’re too hot or too cold in bed, you'll struggle to fall asleep and it will lead to frequent wake-ups throughout the night, causing sleep depravation and leaving you feeling fatigued the next day. Here what you need to know...
What is the best temperature for sleeping?
A new study shows they optimal sleep temperature for quality sleep is between 20 and 25 °C (68 and 77 F). The study, which was conducted in Boston, analysed the sleep and temperature habits of 50 people over a total of 10,903 nights of sleep.
The study showed that, “bedroom nighttime temperature was associated with duration, efficiency, and restlessness of sleep.” With Dr. Chris Winter, Sleep expert, neurologist and MD of Mattress Firm explaining that: “the area in the brain responsible for temperature maintenance and sleep circadian rhythms are quite close to one another, therefore affecting your sleep.”
Why is sleep temperature so important?
Our sleep is regulated by our circadian rhythm – the sleep and wake cycle, which produces the hormone melatonin to make us feel tired at night and wake us up in the mornings. However, factors such as too much caffeine, light and temperature can impact our sleep.
Your body temperature naturally fluctuates throughout the day, but it tends to drop as you prepare for sleep. So a cooler sleep environment helps facilitate this natural drop in body temperature, signalling to your body that it's time to sleep.
As we sleep your body goes through a process known as thermoregulation - maintaining a stable internal temperature. This study shows that sleeping in a room that is too hot can interfere with this process, leading to discomfort and potentially waking you up.
“Despite far more attention being given to the need for a drop in ambient light in order for sleep to be optimized, there is a similar response to a drop in ambient temperature. In this study, the temperature range of 68-77 degrees F was optimal (other studies have shown even slightly cooler temperatures to be optimal),” says Dr Winter.
“This mirrors our body's intrinsic temperature curve that shows we are most awake and alert at 4pm or so, when our body's temperature is at its peak. As our temperature starts to fall rapidly, that is the time we tend to feel most sleepy and seek rest. Creating higher highs (exercise, saunas) and lower lows (lower thermostat, cooling beds, light bed clothes, etc.) trends to amplify this relationship and support sleep,” he adds.
Does being too hot or too cold affect sleep differently?
Not only can extreme temperature make it difficult for us to get to sleep, think sticky sheets or shivering in bed, it could also effect our sleep stages. So, when it’s boiling outside, and you can’t quite get the temperature right in your bedroom how can it affect our sleep?
“When the temperature is too hot, it can make it difficult to fall asleep and stay asleep, disrupt sleep stages, increase sweating, and lead to dehydration,” explains Dr. Shelby Harris, Director of Sleep Health at Sleepopilis and a licensed clinical psychologist who specializes in behavioral sleep sleep medicine.
A study in 2012 on how temperature effects our sleep backed this up, with the study concluding that when we’re too hot it can affect slow wave sleep and REM sleep.
Although a colder temperature, the study explains, won't have an effect on our sleep stages, instead Harris says that it can, “make it difficult to fall asleep, cause superficial sleep, increase muscle tension, and increase the risk of illness. To ensure optimal sleep quality, it is important to create a sleep environment that is comfortable and conducive to relaxation.”
Pro tips for maintaining the best sleep temperature
1. Shower before bed
Extreme temperatures outside can impact the temperature inside so taking a cool shower or warm bath before bed can help regulate your body temperature. This helps lower your body's core temperature, so you'll have an easier time falling asleep. You can even use a hot water bottle to get to sleep fast in cold weather.
2. Choose breathable bedding and PJs
If your bed sheets constantly make you feel overheated, even in the middle of winter, it could be time to reinvest in more breathable bedding. So what should you opt for?
“Cotton and linen are good choices for bedding, as they allow your body to breathe,” explains Harris. While she also goes on to say that you should also: “Avoid using heavy blankets or comforters, as these can trap heat and make you feel too hot.”
As for what you should wear in bed, keep it light. If you think layering up with your thickest PJs are a good idea on super-cold nights, think again as they could make you feel too hot to sleep. “Dress lightly and let the bedding do the work,” advises Winter.
3. Avoid exercising close to bedtime
Exercise is great for sleep but evening workouts, especially too close to bedtime, can raise you body’s core temperature too much before bedtime. Dr Winter explains “That temperature bump will work against your sleep goals,” meaning your body doesn’t have a chance to cool itself, working against the temperature in your bedroom. So if you really want to get that evening workout in, try and finish no later than 7pm - so your body has a chance to cool before you slip under the sheets.
4. Get a temperature regulating mattress
Beds and pillows come in all shapes and sizes, with technology which can help you sleep better and even cool you as you sleep. The best mattresses help to regulate your temperature, while the pillows not only support your head and neck but also keep you cool as you sleep. So if your bedding has seen better days, it could be time to invest in something new to help you get that quality sleep you’ve been craving.
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Sarah is a freelance writer who has been published across titles including Woman & Home, The Independent, and the BBC. Sarah covers a variety of subjects, including health and wellness. For Tom's Guide Sarah often writes about sleep health and hygiene, and interviews leading sleep experts about common issues such as insomnia and sleep deprivation.