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.

The impact of temperature on your sleep

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.

How being warm can disrupt your sleep

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.

How being cold can disturb your circadian rhythm

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.

How to maintain an optimal bedroom temperature

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:

1. Change your bedding in line with the season

In the warmer months, try using summer bedding and avoid heavy tog duvets or thick blankets that can trap heat. If you tend to overheat, opt for cooling fabrics to help regulate your temperature and keep you comfortable.

On the other hand, during the colder months, a thicker duvet and a few extra layers of winter bedding might be just what you need to stay cosy. But be careful not to overdo it. Too many layers could make you too warm, causing those middle-of-the-night wake-ups.

2. Have a warm bath before bed

It might sound surprising, but taking a warm bath before bed can actually help your body cool down and prepare for sleep. The warmth of the bath causes blood to flow away from your core and into your extremities, mimicking the natural cooling process your body goes through as it winds down for the night.

In fact, research shows that spending just ten minutes in a warm bath within an hour of bedtime can help you fall asleep faster and improve your sleep quality. It can even reduce the chances of waking up during the night, leaving you feeling refreshed and ready to start the day.

3. Consider your sleep attire

Just like your bedding, the pyjamas you choose can make a big difference to your sleep quality. Thick fabrics and synthetic materials tend to trap heat, causing your body temperature to rise and making it harder to settle into restful sleep. While that cosy, fluffy jumper is perfect for snuggling up before bed, it’s best to switch to something lightweight and breathable when it’s time to sleep. Opt for natural fabrics like cotton, which will feel comfortable and cool on the skin.

For more advice, read our article on what to wear to bed.

4. Close your curtains during the day

Curtains can be a great tool for regulating room temperature, as they minimise heat and airflow that can come through a window. Keeping them closed can not only prevent cold air from coming in during the winter, but it can also block out sunlight, which can increase room temperature during the hotter months. Though sunlight is important for your circadian rhythm during daylight hours, keeping your curtains closed in the evening and in the run-up to bedtime can help keep your room at a comfortable temperature while you sleep.

5. Regulate your room temperature

Though it may be tempting to crank the heating up on those crisp winter nights, make sure to turn it down a notch before you go to bed. Aim for a temperature between the recommended 18-21°C for the duration of the night to ensure that the heat doesn’t affect your sleep. If you need a bit of extra warmth to get cosy in bed, try using a hot water bottle to settle in, but make sure to remove it before you drift off. On hotter nights, if you don’t mind the noise, use a fan to keep cool.

6. Open your window

Particularly important in the summer, keeping a window open during the night encourages air circulation, lowering humidity that can cause a room to feel stuffy. Proper ventilation can help with body temperature regulation, supporting the natural drop in temperature as you fall asleep. If you live on a busy street and the noise makes keeping the window open challenging, try opening it for about an hour before bed to let in some fresh air.

7. Use separate duvets

A popular choice in many Scandinavian countries, using a separate duvet from your partner can make a big difference to your sleep. It prevents body heat transfer, allowing each person to regulate their own temperature, thus supporting their individual circadian rhythm.

With separate duvets, you can also choose the tog that works best for you, optimising your sleep environment to suit your personal preferences.

Read more about the Scandinavian method and how it could improve your sleep.

How to measure your bedroom 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.

What is the optimal temperature for a baby’s room?

A subtle 1-2°C increase on the thermostat will ensure that your baby is warm and comfortable. Since infants can’t regulate their body temperature as effectively as adults, it’s essential to avoid overheating. The ideal temperature for a baby’s room is between 16–20°C (60–68°F). Anything above 20°C can increase the risk of overheating, which has been linked to sudden infant death syndrome (SIDs).

For more information on creating the optimal sleep environment, read out helpful article on how to regulate the temperature of your baby’s room.

What is the optimal bedroom temperature for the elderly?

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.