Key Takeaways
- Temperature matters because sleep and thermoregulation are closely connected. Your body redistributes heat towards the skin around sleep onset, helping core temperature decline.
- Older adults may sleep well at warmer temperatures than commonly quoted advice suggests.
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📖 5 min readHere’s a fascinating part of sleep biology: falling asleep is linked not simply to “getting cold”, but to moving heat from the centre of your body towards your skin so it can escape. Research has found that this heat-loss process is a particularly strong predictor of how quickly you fall asleep (R).
That means your bedroom temperature can influence more than whether you feel comfortable under the covers. Your thermal environment interacts with core body temperature, skin blood flow and the biological processes involved in sleep.
So, what is the best temperature for sleep? There isn’t one scientifically established number that suits everybody. Research suggests that a comfortably cool environment generally supports sleep, but your ideal temperature depends on your age, bedding, clothing and individual physiology. Importantly, a recent real-world study of adults aged 65 and over found that sleep was most efficient and restful when bedroom temperatures were between 20°C and 25°C (R).
There May Not Be One “Perfect” Temperature
Your ideal sleep temperature can depend on your age, bedding, sleepwear and individual physiology. Research in adults aged 65 and over suggests that 20°C to 25°C may be a useful starting range, but individual preferences can vary considerably.
What Bedroom Temperature Is Best for Sleeping?
If you have heard that every bedroom should be set to 16°C, 18°C or another precise number, the science offers a more personalised picture. Studies using controlled sleep environments show that temperature interacts with bedding and sleepwear. For example, a study of healthy young adults comparing bedroom temperatures of 17°C and 22°C found differences in sleep stages and sleep onset, partly depending on the clothing participants wore (R).
For older adults, newer real-world evidence is especially interesting. Researchers monitored 50 community-dwelling adults aged 65 and over for almost 11,000 person-nights, measuring their bedroom environment alongside sleep duration, efficiency and restlessness. Sleep was most efficient and restful between 20°C and 25°C, while sleep efficiency declined by approximately 5–10% as bedroom temperature increased from 25°C to 30°C (R).
There was also substantial variation between individuals. That is an important reminder that the best sleep temperature is better thought of as a personal comfort range, rather than a single thermostat setting for everyone.
What the Research Found
In a real-world study involving adults aged 65 and over, sleep was generally most efficient and restful when bedroom temperatures were between 20°C and 25°C. Sleep efficiency fell as conditions became considerably warmer, highlighting the importance of finding your own comfortable range.
Why Does Body Temperature Matter for Sleep?
To understand why your bedroom temperature matters, it helps to understand thermoregulation, the biological process your body uses to control its internal temperature. Before habitual sleep, blood vessels in areas such as your hands and feet can dilate, allowing more warm blood to reach the skin and increasing heat loss to your surroundings.
Research has found that this heat transfer from the central to the peripheral parts of the body is closely associated with sleep onset (R). Interestingly, warmer skin does not necessarily mean your whole body is getting hotter. In a controlled experiment, mild skin warming accelerated sleep onset, supporting the idea that increased cutaneous blood flow can help dissipate internal heat (R).
This helps explain why an overly warm bedroom can be disruptive. Your body needs to manage heat effectively throughout the night, and excessive environmental heat can make that process more difficult.
In an experimental study of adults over 65, sleeping at 30°C rather than 27°C reduced total sleep time by around 26 minutes and sleep efficiency by 5.5 percentage points. REM sleep was also reduced, while time awake increased (R). So rather than aiming for the coldest room possible, the goal is to create a thermally comfortable environment that lets your body regulate its temperature without having to work against excessive heat or cold.
Your Hands and Feet Help Release Heat
Around sleep onset, blood vessels near the skin can dilate, increasing blood flow to areas such as your hands and feet. This helps move heat away from the centre of the body and supports the natural decline in core temperature associated with sleep.
How Can You Naturally Cool Your Bedroom?
If your bedroom becomes warm overnight, you do not necessarily need to make dramatic changes. Improving airflow and reducing unnecessary heat can help create a more comfortable sleeping environment. Ventilation is particularly interesting because bedroom air quality and temperature can interact. In an experimental study involving people over 65, improved ventilation increased the duration of deep sleep and REM sleep under the conditions tested (R).
When outdoor conditions allow, you can encourage airflow by opening windows in the cooler evening or early morning and closing them when outdoor temperatures rise. A fan can also increase air movement, though how comfortable it feels depends on humidity, room temperature and your individual preferences.
Your bedding and sleepwear matter too. Fabrics create a small thermal environment around your skin, meaning the thermostat reading is only part of the picture. A controlled Australian study found that sleepwear material influenced sleep onset and other sleep measures across different room temperatures, demonstrating how clothing and environmental temperature interact (R).
A practical approach is to adjust one variable at a time. Try changing airflow, bedding weight, sleepwear or your thermostat, then notice how comfortably you sleep. Your goal is not to chase a perfect number, but to create an environment where you are neither overheating nor feeling uncomfortably cold.
Try Changing One Thing at a Time
Airflow, bedding, sleepwear and room temperature all contribute to your personal sleep environment. Adjusting one factor at a time can make it easier to identify the combination that feels most comfortable for you.
Does the Best Sleep Temperature Change as You Age?
Yes, it may. Ageing is accompanied by changes in thermoregulation, which makes research conducted specifically in older adults particularly useful for understanding sleep environments. One laboratory study involving healthy older men found that sleeping at 32°C rather than 26°C increased wakefulness, reduced REM sleep and suppressed the normal overnight fall in rectal temperature (R).
More recently, researchers studying older adults in their own homes found a non-linear relationship between temperature and sleep. Both cooler and warmer conditions outside an individual’s optimal range were associated with less efficient sleep, while the group-level optimum occurred between 20°C and 25°C (R).
Perhaps the most useful finding was the amount of individual variation. Your preferred sleeping temperature may differ from somebody else’s, even if you are the same age. For healthy ageing, personalisation is a sensible strategy. A comfortable bedroom, suitable bedding, good airflow and attention to how refreshed you feel in the morning can help you identify the environment that works for you.
Frequently Asked Questions About Sleep Temperature
Sleep temperature advice can sound surprisingly precise, but the research paints a much more individual picture. Here are answers to some of the most common questions about bedroom temperature, ageing and sleep.
Is 18°C the best temperature for sleep?
Not necessarily. Although 18°C is commonly recommended, research does not establish it as a universal optimum for every person. Studies show that factors including age, bedding, sleepwear and individual physiology influence thermal comfort during sleep (R).
What is the best sleep temperature for older adults?
A 2023 longitudinal study of 50 adults aged 65+ found that sleep was most efficient and restful at bedroom temperatures between 20°C and 25°C. However, researchers also found substantial differences between individuals, so this should be viewed as a research-based range rather than a prescription for every older adult (R).
Is it better to sleep in a cold or warm room?
Neither extreme appears ideal. The aim is thermal comfort that allows your body to regulate and release heat effectively. Experimental evidence shows that excessive heat can increase wakefulness and alter sleep architecture (R).
Can a bedroom be too hot for sleep?
Yes. In older adults, research has found that increasing bedroom temperature from 25°C to 30°C was associated with a 5–10% reduction in sleep efficiency (R). Laboratory research has also found poorer sleep measures during hotter sleeping conditions (R).
Why do I feel warmer or colder than my partner at night?
Individual differences in physiology, clothing, bedding and thermal preference can all influence how comfortable a particular room temperature feels. The substantial person-to-person variation observed among older adults underscores that a single “perfect” sleep temperature is unlikely to suit everyone (R).
Should you change your bedroom temperature as you get older?
It may be worth reassessing what feels comfortable rather than automatically following temperature advice designed for younger adults. Evidence from people aged 65+ suggests that many older adults can sleep efficiently within a 20–25°C range, although individual preferences vary considerably (R).
The Bottom Line
The best temperature for sleep is one that supports your body’s natural thermoregulation without leaving you excessively hot or cold. Rather than focusing on a universal thermostat setting, research increasingly supports a personalised approach. For older adults in particular, evidence suggests that 20–25°C can be a useful starting range to explore, while recognising that your own optimal temperature may sit outside it (R).
