It’s a common conflict among bed partners: One person wants the bedroom to be almost tropical, so they can sprawl out on top of the covers, wearing little to nothing; the other likes it on the colder side so they can snuggle up under the duvet. Besides leading to ongoing battles over control of the thermostat, these disparate desires beg the question: Is there an ideal temperature for sleep?
The answer is: Yes! “Somewhere between 65 and 67 degrees yields the most sleep continuity, efficiency [the ratio between how much time someone spends asleep to how much time the person spends in bed], and depth of sleep,” says Dr. Chris Winter, a Sleep.com sleep advisor and sleep neurologist in Charlottesville, Virginia. “Humans tend to sleep better in cooler temperatures, whereas heat is disruptive to sleep. It leads to more awakenings.” If that sounds cool, there’s a larger zone: Many sleep researchers say that between 60 and 67 degrees Fahrenheit (15.5 and 19.4 degrees Celsius) is the ideal room temperature for sleep.
From falling asleep to staying asleep and spending enough time in the various stages of sleep for restoration, read on to learn how big of a role heat and cold play when it comes to your sleep quality and why ventilation may play a big difference despite the temperature.
Why temperature can affect the quality of your sleep
One of the most common tips for good sleep hygiene is: Keep your bedroom dark, quiet, and cool. However, in addition to ambient temperature, there’s another factor that controls sleep regulation: your body temperature.
1. Temperature drops tell your body it’s time to sleep
Your body’s circadian rhythms — the internal, biological processes that regulate the sleep-wake cycle, body temperature, and many other essential functions — reach their daily peak between 4 and 6 p.m. and start dropping around bedtime. Your body temperature is included in these drops.
This body temperature drop is a natural trigger for sleep, Winter explains. “Sleep is controlled in the brain stem and the hypothalamus, which regulates body temperature,” he says. Once your body temperature goes down, it remains low while you sleep, then rises again one to two hours before you wake up.
2. High temperatures can make it harder to fall asleep
Research has found, however, that ambient room temperature may disrupt your sleep by affecting your body’s ability to regulate its internal temperature.
In particular, sleeping in a warm room can prevent your body from lowering its internal thermostat appropriately during the night, which would help facilitate uninterrupted sleep. This can make it harder to fall asleep or stay asleep throughout the night.
In a 2020 study, researchers analyzed data from more than 3.75 million nights and found that people's bedroom temperature was above 70°F for 69% of the nights, with the average temperature ranging between 68.8 and 76.2°F. For each 1°F increase in bedroom temperature between 60-85°F, sleep efficiency decreased by 0.06%, and higher bedroom temperatures were linked to shorter total sleep time duration, longer sleep onset latency, and longer episodes of being awake after sleep onset.
3. Extreme temperatures can wake you up at night
Ambient temperature extremes also increase spontaneous arousals, Winter says. After a night spent tossing and turning in a pool of sweat or after hours of trying to burrow beneath the covers to get warm, it’s no wonder you feel tired in the morning.
Even if you don’t remember trying to get comfortable at night, it’s possible to have experienced disrupted sleep due to temperature shifts. “Some of [the awakenings] you might be conscious of, and some of which you might not,” Winter confirms.
4. High temperatures can reduce deep and REM sleep quality
What’s more, ambient temperature extremes that leave you shivering or sweating lessen deep sleep and REM sleep, Winter says.
Interestingly, research has found that the body’s ability to regulate its temperature is suspended during REM sleep for reasons that aren’t understood. But decreases in REM sleep due to the ambient temperature being too high or too low can lead to more fragmented sleep and leave you feeling unrestored in the morning. “A decrease in REM and slow-wave sleep also impacts recovery from stress and decreases function of the immune system,” notes Thomas Kilkenny, director of the Institute of Sleep Medicine at Northwell Staten Island University Hospital in New York.
This is another reason why it’s important to have your sleeping environment in the optimal temperature zone — to take the pressure off your body to regulate its own temperature.
Unfortunately, climate change may make it even harder to regulate ambient temperature, hence sleep quality. A 2022 study found that rising temperatures around the world are already eroding people's sleep quality and quantity—and the problem is expected to get a lot worse with continued climate change.
“People in the warmest regions are expected to lose the most amount of sleep due to the hottest ambient temperatures,” Kilkenny says. “If people do not start to adapt to rising temperatures, they may start to lose significant amounts of sleep. Solutions need to be developed to reverse these changes. If rising nocturnal temperatures persist without an effective solution, nighttime warming due to climate change may eventually reduce the ability of a person to acquire sufficient sleep to function properly.”
The ideal sleep temperature for infants and children
While some experts advise keeping a baby’s room temperature between 68° and 72°F (20 to 22°C), Winter believes this recommendation is based more on theory than scientific evidence. But it is true that babies don’t have the same ability to regulate their body temperature as adults do, Winter notes.
And since it isn’t safe for them to sleep with covers or a blanket because of risks of suffocation — and blankets could cause overheating, which increases risk of Sudden Infant Death Syndrome (SIDS) — it’s important to follow the Goldilocks principle and stick with an ambient temperature for your baby’s room that’s neither too hot nor too cold.
“As kids grow, their metabolisms are strong, and they generate a lot of heat,” says Winter, author of “The Rested Child.” Older children and teens may benefit from sleeping with lighter bedclothes and bed coverings that they can add on or take off on an as-needed basis.
The ideal sleep temperature for older adults and seniors
When it comes to adulthood, hormonal fluctuations during menopause often cause hot flashes and night sweats, which can severely disrupt a woman’s quality of sleep. It may help women going through the menopausal transition to sleep in a slightly cooler room and to wear pajamas that are made with moisture-wicking fabrics; placing a fan nearby or using cool bedding or a cooling pillow can also make a difference, Winter says.
Keeping the bedroom cool can also help people with obstructive sleep apnea, which becomes more common as people get older. In fact, a 2021 study found that when adults with sleep apnea slept in an environment where the temperature was 60°F (16°C), they slept longer, had higher sleep efficiency, and felt significantly more alert in the morning compared to when they snoozed in a setting where the temp was 75°F (24°C).
Temperature tips for regaining snooze control
Rest assured (pun intended): “Sleeping in the wrong temperature won’t make you sick,” Winter says. But it may put you at risk for poorer sleep, which can compromise the way you feel and function throughout the day.
In general, he says it’s better to skew on the colder side than the warmer one in the bedroom because cold reduces inflammation in the body, which is beneficial to your overall health.
“If 65 degrees is too cold for you, try setting the thermostat to 69 degrees for a week, then dropping it by a degree,” Winter advises. “You have to do the experiment yourself.”
“Generally, cooler but comfortable ambient temperatures are appropriate for most people —however, the right temperature often needs to be individualized,” explains Dr. Phyllis Zee, M.D., Ph.D., a professor of neurology and director of the Center for Circadian and Sleep Medicine at the Northwestern University Feinberg School of Medicine in Chicago. “Some people are hot or cool sleepers, and older adults may prefer warmer sleep environments.” In other words, you need to find the sweet spot, temperature-wise, for you.
Also, consider enhancing the ventilation in your bedroom. In a 2023 study, researchers examined the effects of altering the ventilation in 29 actual bedrooms — by remotely changing the fan speed of the exhaust ventilation system without the participants’ awareness — to gauge the impact on sleep quality. They found that when the room had lower ventilation, the participants had significantly less deep sleep, more light sleep, and more awakenings during the night. By contrast, these sleep parameters improved when the fan speed increased for better bedroom ventilation. Interestingly, the bedroom temperature didn’t change with these ventilation adjustments.
Some other strategies that may help enhance your sleep environment throughout the seasons:
If your room is too cold:
While it’s generally easier to fall asleep while it’s chilly, it’s possible for an ambient temperature to get too cold, especially when sleeping in different locations, like a home without proper insulation or a tent.
- Place an extra blanket (or two) on the bed that you can pull on or off as needed.
- Put socks on your feet. A 2018 study found that wearing socks to bed in a cool environment reduces the onset of sleep and sleep awakenings and increases total sleep time and sleep efficiency. The theory is that warming the feet this way might activate the thermosensitive neurons in areas of the brain that regulate sleep.
- Hug a warm compress or water bottle to sleep. Or place it at the foot of your bed so that it can work in a similar way to wearing socks. Wrap the bottle or compress in a towel if it is too hot initially.
- Take a warm bath or shower before turning in. Research shows that it helps people fall asleep faster and improves sleep efficiency. The reason: After your body temperature is elevated by exposure to warm water, it drops a short while later, which sets the stage for sleep.
If your room is too hot:
Hot sleep is also a tricky situation to navigate, as there are many causes, from hot flashes to heat waves, but it’s not impossible with a little planning ahead.
- Use a fan to keep the air circulating. Research shows that improving airflow reduces awakenings while sleeping in warmer weather.
- Wear lightweight pajamas — or sleep naked — to optimize your body’s ability to cool itself.
- Invest in cooling bed technology — mattress pads, pillows, sheets, and more — for your bedroom. A 2003 study found that using a cooling pillow during sleep decreases the body’s sweat rate under humid heat conditions. The same effects can occur with other cooling technology for the bed.
- Open the window. Fresh air can help ventilate the room and help maintain your ideal ambient temperatures when/if you don’t have an AC unit.
Of all the sleep hygiene tips, regulating ambient temperature — or your body temperature — goes a long way in facilitating better sleep. If you are looking for the most effective way to improve your sleep quality, try making sure the temperature of your room is just right.
