For many adults, a comfortably cool bedroom of around 17–19°C is a useful starting point for sleep. However, 15.5–19.5°C is not a medically required range, and there is no single ideal sleeping temperature that suits everyone. Your age, bedding, sleepwear, humidity and personal comfort can all change what feels right.
If you're wondering about the optimal temperature for sleeping in Celsius, this guide explains the evidence, compares bedroom temperatures and shares practical ways to stay comfortable through Australian summers and winters.
What Is the Ideal Sleeping Temperature in Celsius?
The Australian Sleep Health Foundation's guidance on sleeping during hot nights describes approximately 17–19°C as a helpful sleep-temperature reference. Many adults find a slightly cooler bedroom comfortable, especially under suitable bedding.
You may also see recommendations of 15.5–19.5°C, sometimes converted from Fahrenheit. Treat this as a rough guide, not a temperature you must maintain. Other experts suggest a somewhat warmer room, and research in older adults has found that individual preferences and age can make a difference.
Practical answer: Start with a comfortably cool room, notice whether you wake up too hot or cold, and adjust by a degree or two along with your bedding. Your actual comfort matters more than hitting an exact number on the thermostat.
Bedroom Temperature for Sleep: Celsius Comparison Chart
These temperatures are illustrative comfort ranges, not medical thresholds. A lightweight sheet at 21°C may feel cooler than a heavy doona at 18°C.
|
Bedroom temperature |
How it may feel |
What to consider |
|
15–17°C |
Cool for many adults |
Comfortable with appropriate bedding for some; too chilly for others |
|
17–19°C |
Common cool-bedroom starting range |
Often suggested for adult sleep, but not a universal requirement |
|
19–22°C |
Mild to comfortably warm |
May work well depending on age, bedding, humidity and preference |
|
23–25°C |
Warm for some sleepers |
Consider lighter bedding and airflow if you feel overheated |
|
Above 25°C |
Can be difficult on hot or humid nights |
Heat may disturb sleep; prioritise effective and safe cooling |
Note: Temperature alone doesn't determine sleep quality. Air movement, humidity and the warmth of your bedding also affect the microclimate around your body.
Why Does Bedroom Temperature Affect Sleep?
Your core body temperature changes overnight
Your body follows a roughly 24-hour circadian rhythm. Core body temperature generally begins falling as you prepare for sleep and reaches a lower point during the night. Releasing heat through your skin is part of that process.
A very warm bedroom can make it harder to lose heat comfortably. A room that's uncomfortably cold can also make you restless. Neither extreme is ideal simply because it changes the thermometer reading.
Overheating can interrupt sleep
When you feel too hot, you may kick off the doona, turn over frequently or wake to find a cooler position. Warm, humid conditions can be particularly uncomfortable because moisture evaporates less readily from the skin.
Temperature-related interruptions can affect sleep continuity. They do not mean that every warm night causes a measurable loss of REM or deep sleep, and cooling your bedroom does not guarantee a specific sleep-stage percentage. For an explanation of normal sleep stages, read our guide to deep, light and REM sleep.
Bedroom temperature is different from bed temperature
The temperature inside your bedding can be warmer than the air in the room. A thick doona, sleepwear and a mattress surface can all affect how much heat and moisture stay close to your body. This is why two people sharing a room at the same thermostat setting can feel completely different.
Is 15.5–19.5°C Really the Best Temperature for Everyone?
No. The often-quoted 15.5–19.5°C range is a reasonable reference for some adults, not a universally proven optimum. The evidence is mixed across populations, and it matters whether researchers measure room temperature, skin temperature or sleep experience.
For example, a 2023 observational study of older adults found sleep was generally most efficient at 20–25°C within that particular study group. That result does not establish 20–25°C as the ideal range for all older adults, just as 17–19°C isn't a target for everyone else.
Use published temperature ranges as starting points and adapt them to your actual room, health needs and comfort. Do not force your bedroom to become uncomfortably cold to follow a generic recommendation.
How to Keep Your Bedroom Comfortable in an Australian Summer
- Block daytime heat. Close blinds or curtains on sun-exposed windows before the room heats up.
- Ventilate when outside air is cooler. Open windows in the evening or early morning where it is safe and practical; close them when outdoor air is hotter, smoky or unsuitable.
- Choose lighter bedding. Switch a heavy doona for a sheet or lighter covering and adjust your sleepwear.
- Use moving air appropriately. A fan can improve comfort by moving air over your skin, although it doesn't reliably lower the room's actual air temperature. During extreme heat, a fan alone may be insufficient.
- Use cooling or dehumidification if needed. Air conditioning may help when indoor heat or humidity remains high. Choose an achievable, comfortable setting rather than assuming it must be 16°C.
- Think beyond the thermostat. If the bed itself feels hot, review your sheets, protector and mattress materials. Our hot sleeper's guide to choosing a cooling mattress explains the product factors separately.
In Perth's dry summer heat, daytime shading and evening ventilation can be useful. In humid conditions, including some northern and coastal areas, reducing humidity and maintaining safe cooling may matter just as much as the temperature reading.
What Is a Comfortable Bedroom Temperature in Winter?
You don't need to sleep in a freezing room. If 17°C leaves you shivering or repeatedly waking, use warmer bedding or adjust the heating to a comfortable setting. Layered bedding makes it easier to respond if the room cools down overnight.
If using a heater or electric blanket, follow the manufacturer's safety advice. Avoid blocking ventilation around heaters, and use electric bedding only as its instructions permit. The goal is comfortable sleep, not maximising energy savings through an unverified temperature rule.
Do Bedding and Mattress Materials Change How Warm You Sleep?
They can change how the bed feels, but a product can't guarantee a cooler core body temperature or better REM sleep.
Breathable fabrics can allow air or moisture to move differently, while insulating layers help retain warmth. Cover design, weave, fit, moisture, the mattress protector and bedding combinations all matter.
DuuDuu's bedding collection includes TENCEL™ Lyocell sheets and a waterproof mattress protector. Compare their materials and care details, and remember that a mattress protector can change the feel of the surface beneath your fitted sheet.
The DuuDuu Hybrid Mattress is described as using a woven cooling-fabric cover, latex and pocket springs. These are construction features to compare, not proof that it maintains a particular bedroom temperature or treats night sweats.
How to Find Your Own Best Sleeping Temperature
Try a straightforward approach rather than making your bedroom colder every night:
- Measure the temperature near your bed with a reliable room thermometer.
- Start at a comfortably cool setting; around 17–19°C is one useful reference if practical.
- Keep your usual bedtime and sleep routine reasonably consistent for a few nights.
- Notice how often you wake feeling hot, cold or uncomfortable.
- Adjust the room, bedding or sleepwear one variable at a time.
- Consider humidity, airflow, your partner's preference and seasonal changes.
Frequent night sweats, fever, persistent insomnia or other concerning symptoms should not be assumed to result from bedroom temperature alone. Speak with a health professional where appropriate.
Frequently Asked Questions About Ideal Sleeping Temperature
What is the best temperature for sleeping in Celsius?
Around 17–19°C is a commonly suggested starting range for adults, but the best temperature is the one that keeps you comfortably cool without feeling cold. Bedding, humidity, age and individual preference can shift that range.
Is 19°C a good temperature for sleeping?
Yes, 19°C can be comfortable for many adults. Adjust bedding and airflow to suit how you feel. There is no evidence that an exact setting of 19°C is required for healthy sleep.
Is 15.5°C too cold to sleep?
Not necessarily, but it may be too cold for some people. A suitable doona may make a cool room comfortable, while someone else may prefer a warmer setting. Don't force a colder room if you feel chilled or sleep poorly.
What is the best bedroom temperature in an Australian summer?
Aim for a safely cool, comfortable room rather than a fixed number. Block daytime heat, use lighter bedding and moving air, and consider air conditioning when the room remains hot or humid. An exact 17°C setting may not be practical or necessary.
Should your bedroom be warmer in winter?
It can be, if you need it for comfort. Your ideal setting may change with bedding and sleepwear. A cool room with a warmer doona works for some adults, but sleeping uncomfortably cold is not the goal.
Does humidity affect the ideal sleep temperature?
Yes. High humidity can make warm nights feel more uncomfortable because sweat evaporates less readily. Airflow or dehumidification may help, depending on the conditions and your home.
Do older adults need a warmer bedroom for sleep?
Some older adults may be comfortable at warmer temperatures. Research has observed different sleep-temperature patterns among older adults, but it doesn't establish one mandatory range. Personal health and thermal comfort should guide adjustments.
Can a cooler bedroom increase deep sleep or REM sleep?
A comfortable temperature may reduce heat-related awakenings, but it cannot guarantee more deep or REM sleep. Sleep-stage patterns depend on many factors, and a mattress or thermostat setting is not a proven way to achieve a particular percentage.
Create a Bedroom That Feels Right for You
The best sleeping temperature isn't a magic number. Begin with a comfortably cool room, keep your bedding suitable for the season and adjust when heat or cold disturbs your sleep.
Visit DuuDuu Australia to browse mattresses, pillows and bedding for Australian homes, and choose sleep essentials based on your comfort and their verified features—not promises about achieving a perfect temperature or sleep-stage score.
