Key takeaways
- The temperature most sleep guidance recommends for a bedroom is 16 to 18°C.
- Sleep tends to suffer above about 24°C, because your body has to lose heat to fall asleep.
- For babies, the Lullaby Trust recommends a room of 16 to 20°C.
- A fan, lighter bedding and cooling the room before bed are the cheapest fixes; only a portable air conditioner lowers the air temperature.
When a heatwave hits, the real question is not whether it is hot but whether it is too hot to sleep. There is a reasonably clear answer. Here is the temperature your bedroom should be, the point where heat starts wrecking your sleep, and what to do about it.
What temperature should a bedroom be for sleep?
Most sleep guidance lands on 16 to 18°C as the sweet spot. The reason is physiological: to fall asleep, your core body temperature needs to drop by around one degree, and a cool room helps that happen. A bedroom much warmer than 18°C makes that harder, which is why hot nights leave you tossing and turning.
How hot is too hot to sleep?
As a rule, sleep quality falls away above about 24°C. Beyond that point you wake more often, spend less time in deep and REM sleep, and feel less rested in the morning, even if you do not remember waking. Humidity makes it worse, because sweat cannot evaporate to cool you, which is why a muggy night feels harder than a dry one at the same temperature.
What about babies and children?
Small children cannot regulate their temperature as well as adults, so the guidance is stricter. The Lullaby Trust recommends keeping a baby’s room between 16 and 20°C and avoiding overheating. A room thermometer and light bedding or sleepwear help you stay in that range during a heatwave.
How to cool a bedroom for better sleep
The cheap fixes come first: keep curtains shut during the day, open opposite windows at night, turn off anything giving out heat, and point a fan to move air over you or push hot air out of the window. If the air itself is humid, a dehumidifier helps. If the room overheats no matter what, only a portable air conditioner lowers the actual temperature. We cover the full list in our guide to cooling a bedroom in a heatwave, plus the best fans and portable air conditioners.
Common questions
What is the best temperature for a bedroom?
Most sleep guidance puts the ideal bedroom temperature at 16 to 18°C. A room in that range helps your body lose the heat it needs to shed to fall asleep and stay asleep.
How hot is too hot to sleep?
Sleep usually starts to suffer above about 24°C. Past that, people wake more often and get less deep sleep, because the body cannot drop its core temperature enough to rest properly.
What temperature should a baby’s room be?
The Lullaby Trust recommends keeping a baby’s room between 16 and 20°C, and avoiding overheating, which is linked to a higher risk of sudden infant death.
How do I cool a bedroom down for sleep?
Block the sun during the day, open opposite windows at night, switch off heat sources, and use a fan to move air over you. If the room still overheats, a portable air conditioner is the only option that lowers the actual air temperature.
Sources: the Lullaby Trust for children’s room temperature, and widely used sleep guidance for the 16 to 18°C adult range.