Why Temperature Matters So Much for Sleep
If you have ever tossed and turned on a hot summer night or woken up shivering because the aircon was too cold, you already know that temperature plays a huge role in how well you sleep. But the connection between body temperature and sleep goes much deeper than simple comfort - it is actually hardwired into your biology.
Your body's core temperature naturally drops by about one to two degrees as you prepare for sleep, and this cooling process is one of the key signals that tells your brain it is time to rest. If your bedroom is too warm, your body struggles to cool down, and falling asleep becomes harder. Understanding the ideal sleep temperature - and how to achieve it - can make a real difference to both how quickly you drift off and how deeply you sleep through the night.
The Sweet Spot: 18 to 20 Degrees Celsius
Most sleep researchers agree that the ideal bedroom temperature for adults falls between 18 and 20 degrees Celsius. This range supports the natural drop in core body temperature that occurs during sleep and helps you stay comfortably cool throughout the night without waking up cold.
For babies and young children, the recommended range is slightly warmer - around 20 to 22 degrees - as they are less able to regulate their own body temperature. If you are not sure how warm or cool your bedroom actually gets overnight, a simple room thermometer can be a helpful guide.
What Happens When Your Room Is Too Warm
Sleeping in a room that is too warm does not just make you uncomfortable - it actively disrupts your sleep architecture. Higher room temperatures have been shown to reduce the amount of time spent in deep sleep and REM sleep, which are the most restorative stages of the sleep cycle. This means you can spend a full eight hours in bed but wake up feeling unrested because your body did not get the quality of sleep it needed.
Warm rooms also increase the likelihood of night sweats, restlessness and frequent waking, all of which fragment your sleep and leave you feeling groggy the next day.
Practical Ways to Cool Your Bedroom
You do not necessarily need airconditioning to achieve a comfortable sleep temperature. There are several simple and affordable strategies that can help keep your bedroom cool, especially during the warmer months.
Use Breathable Bedding
Switching to natural, breathable fabrics like cotton or linen for your sheets and pillowcases can make a noticeable difference. These materials allow air to circulate and help wick moisture away from your body. Heavier synthetic fabrics tend to trap heat and can leave you feeling clammy during the night.
Open Windows Strategically
If the outside temperature drops in the evening, opening a window for an hour or two before bed can help bring the room temperature down naturally. Cross-ventilation, where you open windows on opposite sides of the room or house, is particularly effective at moving warm air out.
Use a Fan Wisely
A fan does not actually lower the room temperature, but the moving air helps evaporate sweat from your skin, which creates a cooling effect. Pointing a fan towards your upper body rather than directly at your face can help you stay cool without drying out your sinuses. If you find the noise from a fan disruptive, sleep headphones can help you mask the sound with something more soothing.
What About Cold Rooms?
While a cool room supports better sleep, a room that is too cold can also be problematic. Sleeping in temperatures below 15 degrees can cause your body to tense up, which makes it harder to relax into sleep and can lead to restless nights. If your room tends to get very cold, layering blankets that you can adjust during the night gives you more control than relying on a single heavy doona.
Your Body Temperature Rhythm
Your body temperature follows a predictable pattern throughout the day, rising during waking hours and dipping at night. This natural cycle is closely tied to your circadian rhythm. Activities that raise your core temperature - like exercise, hot baths or large meals - can temporarily shift this cycle, which is why it is best to avoid intense exercise or very hot showers close to bedtime.
Interestingly, a warm bath taken about 90 minutes before bed can actually help you sleep better. The bath raises your body temperature, and the rapid cooling that happens when you get out triggers a stronger drop in core temperature, which signals the brain that sleep is coming.
Finding What Works for You
While 18 to 20 degrees is the general guideline, everyone is slightly different. Pay attention to how you feel when you wake up. If you are consistently throwing off the covers or waking up sweaty, your room may be too warm. If you are curling up tightly or waking from the cold, it may be too cool. A little experimentation with room temperature, bedding layers and airflow can help you find the combination that works best for your body and your sleep environment.
For more tips on creating a bedroom that supports restful sleep, our guide to creating a sleep-friendly environment covers everything from lighting to noise to the small details that make a big difference. And if you are looking for ways to stay comfortable through the warmer months, our sleep wellness collection has practical solutions designed for Australian conditions.
"I never thought room temperature could make such a difference until I started keeping my bedroom at 19 degrees. I fall asleep faster and actually stay asleep through the night now." - Chris, Perth
"Switching to linen sheets was a game changer for summer sleeping. Combined with a fan and keeping the room around 20 degrees, I went from waking up drenched in sweat to sleeping right through." - Nina, Darwin
