“Some sources recommend an even colder room; however, I typically recommend temperatures at least two to five degrees cooler than a comfortable temperature in the house during the day,” says Dr. Nilong Vyas, founder and owner of Sleepless in NOLA, a sleep consulting service, and medical review expert at SleepFoundation.org.

For example, if you typically keep your home at 78 degrees during the day, then dropping the nighttime temperature to 68 will likely feel too cold and diminish the quality of your sleep. But if your daytime temperature is closer to 68, then cooling your house to 65 degrees is more reasonable, Vyas suggests.

“Don’t get caught up on the exact temperature; ensure it is cooler than comfortable temperatures during the day,” she says.

Why bedtime temperature is important

Your sleep cycle is regulated by your body’s circadian rhythm, which receives its cues from a number of factors, including light exposure, exercise and temperature. Whereas your body temperature is generally around 98.6, it can dip by about two degrees throughout the night, according to research. That drop in temperature also coincides with the release of melatonin, the hormone responsible for sleep.

“Thermoreception is a sensory process wherein the body is able to detect heat in both the body and its environment. During sleep, the skin experiences an increased amount of blood flow, which can lead to a warming sensation,” explains Vyas. “Physiologically, increased blood flow to the skin prevents heat loss and potential hypothermia when humans were living without shelter. However, now that we are not sleeping in the wilderness and have bedding and warm clothes, the physiological nature of warming the skin during sleep is unnecessary.”

If your bedroom is too warm, that can prevent your body from thermoregulating itself and can leave you feeling fatigued and restless—thus enabling you from the recommended seven to nine hours of sleep for adults under 65.

Other ways to keep your room cool (and get better rest)

If you’re cautious about running air conditioning all night, there are other ways to regulate your room’s temperature:

• Close your blinds during the day to keep your room cool
• Open windows to increase ventilation
• Wear light clothing to bed
• Invest in a cooling mattress like a Saatva, bedding, and pillows
• Use a dehumidifier to reduce moisture in the air  

Healthy sleep hygiene habits, such as keeping a regular bedtime and avoiding caffeine, exercise, and alcohol before bed, can also promote optimal rest.

“Lower temperatures facilitate cooling down of the core body temperature, thereby facilitating melatonin release, and may help with less interrupted sleep,” says Dr. Abhinav Singh, medical director of the Indiana Sleep Center and medical review expert at SleepFoundation.org. “Anything under 68 degrees overall is ideal for sleep. If you get too hot in the middle of the night, reduce layers of clothing or sheets, turn on fans, or drink a little cold water.”