What’s the Best Temperature for Sleep?

Whether you’re struggling to fall asleep in the heat or you can’t stop shivering on a chilly winter night, temperature plays a big role in how well we sleep. It can affect not just how easily we drift off but also the quality of our rest once we’re asleep. So, what’s the magic number?

Sleep experts agree that the ideal temperature for a peaceful night’s sleep falls between 18–21°C (65–70°F). While these figures can vary slightly for babies and the elderly, for most adults, sticking to somewhere within this sweet spot will give you the best chance of waking up feeling refreshed and ready to take on the day.

Our bodies are guided by an internal clock, otherwise known as our circadian rhythm, which regulates when we feel sleepy, awake, and everything in between. At night, your body’s thermoregulation (the natural process of maintaining a stable internal temperature) is controlled by this rhythm, causing your core temperature to drop by about 0.5-1°C, signalling to your brain that it’s time to sleep. This cooling effect not only helps you drift into the deeper stages of sleep, such as deep sleep and REM sleep, but also encourages your body to conserve energy by lowering your metabolic rate while you rest.

This temperature drop begins as melatonin, the sleep hormone, starts to rise in the evening. It continues throughout the night, reaching its lowest point in the early hours of the morning. As melatonin levels begin to decrease, your body naturally warms up, signalling that it’s time to wake up.

Keeping your bedroom cool aligns with this natural process, supporting your ability to fall into a restful and undisturbed slumber. The right temperature ensures you get the high-quality rest your body needs to restore and recover overnight.

As most of us have probably experienced, being too hot can make it feel impossible to get to sleep. This is because high temperatures interfere with the natural thermoregulation process, making it harder for your body to cool down and preventing the correct signals from being sent to your brain, telling it that it’s time to rest.

Studies have also found that a higher core temperature can reduce the amount of deep sleep and REM sleep you get, making you more likely to wake up during the night and feel groggy. A lack of deep sleep can also interrupt key restorative processes that take place while you rest, affecting the immune system and memory and even being linked to chronic health conditions such as diabetes.

While being too cold at night might not be as disruptive to sleep as being too hot, it can still have an impact. When the temperature drops too low, it can throw off your body’s natural temperature regulation, disrupting your circadian rhythm. Additionally, when we’re cold, the body produces more melatonin, the hormone that signals it’s time to sleep. While melatonin should naturally decrease as you wake up, on frosty winter mornings, it can remain elevated, leaving you feeling tired and making it harder to get out of bed.

Learn more about how dark mornings affect sleep.

To help maintain a consistent circadian rhythm year-round, try to keep your bedroom temperature between 18-21°C. This will support thermoregulation and promote deeper sleep, leaving you feeling refreshed. Here are some suggestions for keeping your room at the perfect temperature:

To ensure that your bedroom is at the optimal temperature for sleep, it can be useful to use your thermostat or a classic room thermometer. For the most accurate result, place your thermometer in the centre of the room, away from windows, doors, and radiators, as these could affect the reading. Since heat rises, avoid placing the thermometer too high, as it may give you an inaccurate temperature.

As we age, our core body temperature naturally tends to be slightly lower than when we were younger, meaning older adults often need a slightly warmer environment to feel comfortable. Thinner skin, along with age-related medical conditions and medications, can also make it harder to regulate body temperature.

Studies have shown that a room temperature between 20-25°C is ideal for creating the most restful and efficient sleep for older adults.

Though we can’t control the weather, taking the recommended steps to maintain a comfortable bedroom temperature can improve both the quality and duration of your rest. Keeping a cool, stable environment supports your body’s natural circadian rhythm, helping you wake up feeling refreshed and ready to take on the day.