The short version
There isn’t a single bedroom temperature that works perfectly for everyone because people’s comfort levels vary a lot. But many experts, doctors, and sleep researchers agree on some temperature ranges you can try to help improve your sleep. Most say the best bedroom temperature for adults is usually between 60 to 67 degrees Fahrenheit (15.6 to 19.4 degrees Celsius). Some research suggests a slightly warmer range, about 19 to 21 degrees Celsius (66.2 to 69.8 degrees Fahrenheit).
Your ideal sleep temperature can depend on many things like your age, health, and even where you live. If the room is too hot or too cold, it can disturb your sleep, but different studies show different exact temperatures where problems start. Besides the room temperature, it’s important to create a cozy environment with the right bedding that keeps you comfortable. For example, a cool bedroom air combined with soft, warm blankets can work well. Humidity also matters because high humidity can make it harder to sleep well.
At the end of the day, the best bedroom temperature is the one where you feel comfortable and sleep through the night without waking up. Personally, I like my bedroom cool, but some people prefer it warmer. It’s good to try different temperatures to find what helps you sleep best.
The long version
Why I care about the bedroom temperature
I pay close attention to bedroom temperature because I’m sensitive to feeling too hot or too cold at night. Also, I test different bed cooling and heating products, so I know how much temperature affects sleep. I prefer sleeping in a cooler room with cozy bedding. If you live somewhere like the UK, you know how summer heat waves without air conditioning can cause tough nights to sleep.
That’s why I looked into what sleep experts and scientists say about temperature and sleep. Although there is no one perfect temperature that fits everyone, many studies and surveys give useful clues. Temperature is a major factor that affects how well we sleep.
Temperature is a key factor in sleep
Scientists who study sleep agree that temperature is very important. If the room is too hot or too cold, it can make it harder to fall asleep and stay asleep. A study by Japanese researchers in 2012 said the thermal environment is one of the most important things that affect sleep. When it’s too hot or too cold, people wake up more often and spend less time in deep sleep stages. Even healthy people without sleep problems can have their sleep affected by the temperature around them.
This means keeping your bedroom at the right temperature can help you get better rest.
There may not be one ‘ideal’ bedroom temperature for everyone
Even though I sleep best in a cool room, many people I know like warmer rooms. For example, some friends think I’m odd for sleeping with a window open in winter, and my grandma wouldn’t want it cold at all. People’s comfort with temperature varies, so there isn’t one perfect number to set your thermostat at.
Different websites and studies give different temperature suggestions. Most say the bedroom should be cooler, but the range can be anywhere from 60°F (15.6°C) to 72°F (22.2°C). That makes sense because 60°F is quite cool in many places, while 72°F feels like a warm summer day. People in hotter countries may prefer warmer rooms than those in cooler climates.
Some studies show best sleep happens between 61°F (16°C) and 73.4°F (23°C). One research group says 19-21°C (66.2-69.8°F) is ideal. So instead of a single answer, it’s about finding the right balance between room temperature, your bedding, and your body’s natural cooling process when you fall asleep.
Comparing my sleep tracker data in hot and cold weather
I wanted to check if my sleep tracker data would prove that I sleep worse when it’s hot. In July 2021, England had a heat wave lasting about a week. Even though it wasn’t very hot compared to some places, it felt very warm for us, and many people I know said they didn’t sleep well.
The data from my tracker shows that before the heat wave, I slept about 7 hours and 18 minutes a night. But during the heat wave, my sleep dropped to about 6 hours and 41 minutes. My sleep time started dropping from day four of the heat wave and continued to stay lower.
I remember my house, which has no air conditioning, felt hotter every night. It was like the heat built up and made it harder to cool down enough to sleep well. I didn’t change much in my daily habits, so the temperature seems like the main reason for the worse sleep.
Looking at winter sleep, I didn’t notice big improvements compared to before the heat wave, which suggests that excessive heat is more disruptive to my sleep than cold or mild temperatures.
What surveys reveal about people’s temperature preferences
My experience is just one example. Let’s look at what thousands of people say about bedroom temperature and sleep from surveys and studies.
National Sleep Foundation poll
The Sleep Foundation asked 1,500 adults across the U.S. how different things affected their sleep. Bedroom temperature was the second most important factor after pillows. 69% said temperature had a big effect on their sleep. Most people said a cool bedroom is very important to sleep well, with nearly 80% rating it highly.
People in the southern U.S. felt temperature affected their sleep more than those in the northeast.
Sleep, temperature, and climate change
A 2017 study in the U.S. looked at data from over 765,000 people and matched it with nighttime temperatures. They found that as night temperatures rose, people reported worse sleep. This was especially true in summer, for older people, and for those with lower incomes. The researchers warned that climate change may cause more people to lose sleep because nights are getting hotter.Fatigue, sleep quality and air temperature in the summer
A Japanese study from 2015 surveyed over 600 people in summer and found that high air temperatures made poor sleepers feel more tired. Good sleepers were not affected as much. This shows heat in summer can increase fatigue, especially if you already have trouble sleeping.
What medical and sleep websites say about bedroom temperature
Before writing this article, I checked the top 30 search results on Google and Bing for “best temperature for sleep.” Most websites agreed that the ideal bedroom temperature for adults is between 60° and 67°F (15.6° to 19.4°C). But there were small differences in the exact range.
Here’s what five popular medical and sleep websites say (updated July 26, 2024):
Clevelandclinic.org recommends 60 to 67°F (15 to 19°C). Sleep psychologist Michelle Drerup calls the bedroom your “cave” that should be cool, dark, and quiet.
Healthline.com suggests around 65°F (18.3°C), plus or minus a few degrees.
Webmd says set the thermostat between 60 and 65°F for better falling asleep and staying asleep.
Thesleepcharity.org.uk says 16-18°C (60-65°F) is ideal. They warn that rooms over 24°C (71°F) cause restlessness, and rooms around 12°C (53°F) are too cold to fall asleep easily.
Health.com quotes sleep specialist Dr. Chris Winter recommending about 65°F as ideal, but a few degrees warmer is also okay.
Most advice centers around 65°F (18.3°C), with room to try temperatures a little warmer or cooler to find what works for you.
Research studies into the ideal bedroom temperature
Scientific studies have looked at how room temperature affects sleep, but no single study covers a wide range of temperatures to find a perfect number.
One study suggests the ideal room temperature is between 19 and 21°C (66.2 to 69.8°F) because people create a warm “microclimate” under their covers that stays around 31 to 35°C (about 88 to 95°F). This microclimate helps people sleep better, but heating the whole room warmer doesn’t replace this effect.
Another study showed people adjust their bedding during the night depending on room temperature, which helps regulate body heat for better sleep.
Study shows colder temperatures aren’t ideal without bedding or clothing
In the 1980s, a study tested people sleeping with no bedding and wearing only shorts in different temperatures: 21°C, 24°C, 29°C, 34°C, and 37°C. They found 21°C caused the most sleep disruption, and colder temperatures disturbed sleep more than warmer ones.
This shows that sleeping in a cold room without blankets isn’t good. Bedding is important to create the right warm space around your body, supporting better sleep.
High heat and humidity found to be worse for sleep
Japanese researchers in 1999 tested sleep at 29°C and 35°C with different humidity levels. They found that 35°C with 75% humidity caused the worst sleep, with more waking and less deep sleep.
Another study in 2004 found older men had more waking and less REM sleep at 32°C compared to 26°C.
High humidity makes it harder to cool down by sweat evaporation, so hot and humid rooms can seriously reduce sleep quality.
Research in China shows a preference for higher temperatures
A 2011 Chinese study found sleep quality was best at 23°C (73.4°F), higher than the typical advice.
A 2019 study found people slept better when daily maximum temperatures were 32°C or 28°C, and worst when temperatures reached 36°C or 38°C. These findings suggest temperature preferences might differ in warmer climates or countries.
Study into room temperature in patients with sleep apnea
A 2012 study looked at sleep apnea patients in rooms at 16°C, 20°C, and 24°C. They slept longer and better at 16°C but had worse apnea symptoms at cooler temperatures. This shows some health conditions might affect ideal bedroom temperature.
Hot flashes and ambient temperatures study
A study in 2006 tested postmenopausal women’s sleep at 18°C, 23°C, and 30°C. Women had fewer hot flashes and better sleep at 18°C. So cooler rooms help women with hot flashes sleep better.
Older adults may prefer a warmer nighttime temperature
A 2023 study of older adults found the best sleep happened between 20°C and 25°C (68°F to 77°F). Sleep got worse if the temperature went above 25°C.
This means older people might need a slightly warmer room to sleep well compared to younger adults.
Making sense of conflicting ideal bedroom temperature evidence
Some studies support cooler rooms for sleep, especially for people with sleep apnea or hot flashes, while others find slightly warmer rooms better.
What I take from the research is:
Bedding is very important. You need to create a warm, comfortable microclimate under the covers.
Sleeping in a cool room with good bedding is usually better than a hot room with no covers.
Without bedding, cold rooms can disturb sleep more. With bedding, hot rooms are more disruptive.
Very hot or very cold bedrooms tend to make sleep worse.
High humidity also makes sleep harder.
People in different regions may prefer different temperatures because of climate and habit.
Individual needs vary by age and health.
We need more research with lots of people and temperatures to know for sure, but these ideas help explain the general advice.
Why and how does temperature affect our sleep?
A decrease in body temperature signals sleep
Sleep scientists explain that our body temperature and sleep are closely linked. Our body controls its temperature through a process called thermoregulation, which is tied to the circadian rhythm — the natural 24-hour cycle that controls when we sleep, eat, and feel awake.
Before sleep, our core body temperature drops. This cooling signals our body to get ready for sleep. Studies show we fall asleep faster when this temperature drop happens quickly in the evening.
Nest building
Many animals prepare for sleep by curling up or building nests to keep warm. Humans do the same by using mattresses, pillows, blankets, and pajamas.
If it’s too warm, we try to cool down by using less bedding, changing sleep positions, turning on fans, or lowering the thermostat. We do these things both consciously and unconsciously to get comfortable and save energy.
Some types of insomnia may be connected to problems with this body temperature cycle. For example, if your body temperature doesn’t drop enough, you might have trouble falling asleep.
The role of skin temperature in sleep
Research shows that warming your skin, especially your hands and feet, helps your core body temperature drop. This happens because more blood flows to the skin, letting heat escape. This is called vasodilation.
Taking a warm bath before bed (but not right before sleeping) can help you fall asleep faster and sleep more deeply. This warmth around the skin creates a cozy microclimate and helps your body get ready for rest.
Manipulating skin temperature
In 2008, a study found that even a small increase in skin temperature helped people sleep better without changing their core body temperature. This effect was stronger in older adults and people with insomnia.
People with poor circulation, like those with cold hands and feet, may take longer to fall asleep. I personally have Raynaud’s Syndrome, which makes my hands and feet cold, so I like taking warm showers before bed to help.
Putting it all together
The connection between sleep and temperature is more complicated than just making the bedroom cooler. While many people do sleep better in cooler rooms, we still need some warmth around us from blankets or warm baths.
Instead of only focusing on cooling your room, try experimenting with warmth before bed and comfortable bedding. This can help your body get ready for sleep naturally.
Next time I’m too warm in bed, I might wait a little while before uncovering my feet, to see if my body is just cooling itself naturally.
Further reading: how to cool or warm your bedroom and bed
If you want more tips on keeping your bedroom and bed cool or warm, I’ve written two helpful articles:
[Tips for keeping warm in bed]
[Tips for keeping cool in bed]
These guides offer practical ideas to make your sleep environment just right for you.