What's the Best Room Temperature for Sleep?

For most adults, the best bedroom temperature for sleep is about 60 to 68°F (16 to 20°C). Cleveland Clinic suggests 60 to 67°F ^[2], and the Sleep Foundation puts the sweet spot at around 65°F, or 18°C ^[1]. A cool room makes it easier for your body to shed the heat it has to lose to fall and stay asleep. Treat the range as a starting point, because humidity, bedding and age all shift what feels right.

Why your core temperature needs to fall

Your core temperature is not fixed. It rises and falls on a daily rhythm, and sleep sits on the downslope. The drop usually begins about two hours before you fall asleep, around the time your body starts releasing melatonin, and it keeps falling through the night to a low point in the early morning ^[1]. Sleep is most likely to begin while core temperature is falling and hardly happens while it is rising ^[3].

To cool your core, your body opens up blood vessels in your hands and feet and lets heat escape through the skin ^[1]. That is why your feet can feel warm in bed even as your inner temperature drops. It also explains a small, handy finding: warming the feet has been shown to shorten the time it takes to fall asleep ^[3]. People with chronically cold feet may be more prone to trouble falling asleep ^[1].

A warm bedroom fights this process. When the air around you is hot, heat has a harder time leaving your body. A higher core temperature has been linked with less of the deep, slow-wave sleep your body needs ^[1]. For the timing of your own temperature low point, see the circadian rhythm calculator. This page is about the room around you.

Too hot or too cold: what the research shows

You might expect cold to be just as disruptive as heat. For sleep stages, under real-life conditions with pajamas and covers, it is not. A review of thermal sleep research found that heat exposure increases wakefulness and reduces both slow-wave and REM sleep, while cold exposure with adequate bedding does not change sleep stages ^[3]. Cold still leaves a mark, though. It affects the nervous system's control of the heart during sleep, without changing how well you think you slept, and the review's authors suggest cold may matter more in real life than heat for exactly that reason ^[3].

The practical rule: keep the room on the cool side, not cold, and fine-tune with layers. Cleveland Clinic advises that above 70°F is too hot for most people, and below 60°F too cold ^[2].

Humidity and bedding matter as much as the thermostat

Your thermostat measures the room. Your body feels the small pocket of air between your skin and the covers, which researchers call the bed climate. When sleep goes well, that pocket tends to sit at about 32 to 34°C (90 to 93°F) and 40 to 60% relative humidity ^[3]. A heavy duvet in a cool room can create the same bed climate as a sheet in a warm one.

Humidity is the sneaky one. In dry air, sweat evaporates and cools you. In humid air, it stays on your skin, so you keep heating up ^[3]. That is why a 78°F night in a muggy city can feel far worse than the same temperature somewhere dry. Humid heat adds to the load on your body's cooling system and disturbs sleep stages and temperature control during the night ^[3].

Hot nights: what works without air conditioning

Start in the daytime. Closing blinds and curtains on sunny windows stops the room from soaking up heat in the first place ^[1]. In the evening, open the windows once it is cooler outside than in, and keep the air moving with a fan ^[1][2]. If you have a downstairs room, summer is the time to use it, since upper floors trap heat ^[1].

Then strip the bed back to light, breathable sheets and sleepwear so sweat can evaporate. It sounds backwards, but a warm shower may help more than a cold one. In a review of 17 studies, a warm bath or shower one to two hours before bed helped people fall asleep faster, probably because it speeds up the cooling of your core afterwards ^[4].

If hot nights leave you tired all morning despite enough hours in bed, our guide to why you wake up tired covers the other usual suspects.

Cold rooms and cold feet

A cool room is fine as long as you are warm under the covers. If you lie there shivering, add a layer of bedding before you turn up the heat. Warming your feet, with socks or a warm bath, helps for a specific reason: in studies, foot warming shortened the time it took to fall asleep, because heat loss through the skin is part of how sleep begins ^[3]. If your feet are cold every night no matter what you do, mention it to a doctor, since poor circulation has several possible causes.

Older adults and temperature

Ideal temperatures shift with age. In a study that tracked older adults sleeping in their own homes, sleep was most efficient and restful when the bedroom was between 20 and 25°C (68 to 77°F), and efficiency fell by 5 to 10% as nights warmed from 25 to 30°C (77 to 86°F) ^[5]. The researchers also found big differences between individuals ^[5].

Older adults also seem more sensitive to heat than younger ones. Even mild heat raises wakefulness and reduces REM sleep in older people, and it can double the amount of sweat lost overnight ^[3]. On hot nights, that makes cooling the bedroom and drinking enough during the day more important.

If you want to check whether a change is working, track your nights for a week before and after. The sleep efficiency calculator shows how much of your time in bed you actually spend asleep.

Start around 65°F (18°C) and move a degree or two at a time. If you wake up sweaty, go cooler or lighter on the covers. If you wake up curled in a ball, add a blanket.