The ideal sleeping temperature for most adults is between 60 and 67°F (15.6 to 19.4°C). The Sleep Foundation narrows this slightly, recommending approximately 65°F (18.3°C) as the sweet spot. Going above 70°F or below 60°F in your bedroom is likely to disrupt your sleep quality in measurable ways.
Why Your Body Needs a Cool Room
Your core body temperature naturally drops in the hours before sleep. This decline is one of the signals your brain uses to initiate the transition from wakefulness to sleep. The cooling happens because blood vessels in your hands, feet, and skin dilate, moving warm blood from your core to your extremities, where the heat radiates away. A cool bedroom supports this process by giving your body somewhere to dump that heat. A warm room works against it.
Core temperature peaks between 4 and 8 PM, then steadily falls through the night. The speed of this decline actually predicts how quickly you fall asleep. Anything that slows the drop, like a hot room, heavy pajamas, or high humidity, can delay sleep onset and fragment the sleep you do get.
How Heat and Cold Affect Sleep Stages
Not all sleep disruption looks the same. Heat exposure is the bigger problem: it increases the time you spend awake during the night and reduces both deep sleep (slow-wave sleep) and REM sleep, the two stages most important for physical recovery and memory. Humidity makes this worse. Hot, humid conditions suppress your body’s ability to cool its core through sweating, compounding the effect on deep sleep and REM.
Cold exposure is more forgiving. When you’re using normal bedding and clothing, cold temperatures don’t significantly alter your sleep stages. They can, however, change heart rate patterns during sleep, and extreme cold will still wake you up. The takeaway: erring slightly cool is better than erring warm.
The Best Range for Babies and Toddlers
Infants sleep best in a slightly warmer room, between 65 and 70°F (18.3 to 21.1°C). The more important concern is overheating. The CDC warns against letting babies get too hot during sleep, noting that sweating or a hot chest are signs the room or clothing is too warm. Dress infants in one light layer more than you’d wear, and skip heavy blankets, hats, or anything that covers the head.
Older Adults Need a Warmer Room
The standard 60 to 67°F range doesn’t apply as neatly to older adults. A study tracking 50 adults with an average age of 79 over 18 months found that sleep efficiency was highest when bedroom temperatures were between 68 and 75°F (20 to 24°C), notably warmer than the general recommendation. When temperatures climbed more than 9°F above that range, sleep efficiency dropped by 5 to 10%.
This makes sense physiologically. Aging changes the body’s ability to regulate temperature, and older adults often have less muscle mass and thinner skin, both of which reduce heat production and retention. If you’re over 70, the textbook recommendation may leave you too cold for restful sleep. Adjusting upward by a few degrees and paying attention to how you feel is more useful than hitting an arbitrary number.
Humidity Matters as Much as Temperature
A room at 65°F with 70% humidity feels very different from the same room at 40% humidity. High humidity increases wakefulness and cuts into both deep sleep and REM, even when the thermostat reads a comfortable number. Low humidity causes its own problems: dry skin, sore throat, and irritated airways that can wake you up.
The EPA recommends keeping indoor relative humidity between 30% and 50%, with 60% as the upper limit. If you live in a humid climate or run a humidifier, checking actual humidity with a cheap hygrometer is worth the few dollars. Many people overshoot without realizing it.
Practical Ways to Hit the Right Temperature
You don’t need air conditioning set to 65°F year-round. Several low-cost strategies can get your sleep environment into the right zone.
Wearing socks to bed sounds simple, but it works through a real mechanism. Warming your feet dilates blood vessels in your extremities, which pulls heat away from your core faster. Research confirms that this increased blood flow to the feet shifts the temperature gradient between your core and skin in a way that promotes sleep onset. It’s essentially helping your body do what it’s already trying to do.
Your bedding material also plays a role. A systematic review of sleepwear and bedding fibers found that wool sleepwear helped people fall asleep faster, both in cool conditions for younger adults and in warm conditions for older adults. Cotton is a solid all-around choice for sheets because it breathes well. Polyester traps heat and moisture, which works against the cooling process your body needs.
Layering blankets rather than using one heavy comforter gives you more control. You can kick off a layer at 2 AM without fully waking up, which is harder to do with a single thick duvet. Keeping one foot outside the covers is another instinctive move that works for the same reason socks do in reverse: it creates a release valve for excess heat.
Adjustments for Hot Flashes and Night Sweats
Menopausal hot flashes can raise skin temperature by several degrees in seconds, making even an optimally cooled room feel stifling. Layered clothing and bedding become essential so you can quickly shed a layer when a flash hits. Natural fibers like cotton and linen wick moisture better than synthetics. Keeping a portable fan on the nightstand and cold water nearby gives you immediate relief without having to get out of bed. Some people find that cooling the back of the neck with a cold cloth shortens the duration of a flash.
Setting the thermostat a few degrees below 65°F may help if hot flashes are frequent, since you can always add a blanket during cooler stretches of the night but can’t easily cool a warm room mid-sleep.
Finding Your Personal Number
The 60 to 67°F range is a starting point, not a prescription. Your ideal temperature depends on your age, body composition, bedding, what you wear to sleep, whether you share a bed, and even your metabolism. Someone with more body fat generates and retains more heat, so they may prefer the lower end. A lean person or someone on certain medications that affect circulation might need the higher end.
The most useful approach is to start at 65°F and adjust by one or two degrees over several nights, paying attention to whether you wake up during the night, how long it takes to fall asleep, and whether you feel rested in the morning. If you’re consistently kicking off covers, you’re too warm. If you’re curling into a tight ball, you’re too cold. Your body gives clear signals once you start paying attention.