Ideal Room Temperature for Sleeping: What It Is and How to Achieve It

The body needs to cool down to fall asleep. It's one of the conditions for sleep: the internal temperature drops by about 1 ºC as bedtime approaches, and this signal helps trigger rest. A room that is too warm hinders this process. That's why you toss and turn on stuffy nights.

The ideal bedroom temperature for sleeping is between 16 ºC and 19 ºC for most adults. It's not a magic number — it varies with the person, pyjamas, and bedding — but it's the range where the body works least to maintain the right temperature.

Why coolness helps you sleep

Sleep follows the rhythm of your internal temperature. At the end of the day, it drops; in the morning, it rises. A cool room reinforces this nocturnal drop and keeps you in the deep stages of sleep. A warm room does the opposite: the body expends energy trying to cool down, sleep becomes lighter, and you wake up more often without knowing why.

Notice your hands and feet. When you start to get sleepy, they warm up — this is the body releasing heat through the skin to lower its core temperature. A cool room allows this mechanism to work.

How to reach 16-19 ºC in summer

In the Portuguese heat, the challenge is to cool down. Some simple measures:

• Close windows and blinds during the day to block the sun. Open them at night when the air outside cools.
• Create a cross-breeze between two windows or use a fan.
• Choose bedding made of natural fibres, which breathe better than synthetics.
• A lukewarm shower before bed helps: upon exiting, the body cools down.

If you sleep poorly due to heat every summer, I've gathered more strategies in the guide on how to sleep well in the heat.

What about winter?

The common mistake is to overheat. A room at 22-23 ºC with the heating on all night dries the air and fragments sleep. Lower the thermostat to 16-18 ºC and compensate with a warmer duvet. It's more comfortable to sleep in a cool room with good bedding than in a warm, dry room.

Don't forget humidity

Temperature doesn't act alone. The ideal relative humidity is between 40% and 60%. Air that is too dry irritates the respiratory tract; air that is too humid feels stuffy and promotes dust mites and fungi. In winter with heating, the air tends to dry out; on the coastal summer, it tends to rise. Airing the room for 10 minutes in the morning solves most of the problem.

The mattress also counts

The sensation of heat doesn't just come from the air. Some materials retain heat more than others. Traditional memory foam, for example, tends to heat up; pocket spring mattresses allow air to circulate inside and dissipate heat better. If you wake up drenched even with a cool room, the problem might be beneath you. You can see the more aerated options in the spring mattresses collection, and if you have any questions, we'll call you and help you choose in 10 minutes.

A special case: babies

Newborns regulate temperature less effectively and need a slightly warmer room, between 18 ºC and 20 ºC, without overheating. If you have any doubts about your baby's sleep, always follow your paediatrician's guidance.

Temperature is one of the easiest things to adjust and one of the most effective. Combine it with darkness and silence, and you have the essentials of a good bedroom. For other habits, the sleep hygiene guide covers everything, and to set up a bedroom from scratch, you can see how to create the right environment for good sleep.

— Ana Cristina, Sleep Advisor