How Hot Should The Heating Actually Be? Here’s What Scientists Think

Ever found yourself in a full-blown thermostat war with your housemates, partner, or colleagues? You’re not alone. Whether you’re the one bundled up under three blankets while someone else cracks a window, or you’re sweating through winter because someone insists on blasting the heat, finding the “perfect” temperature is trickier than it sounds. But science does have some answers.

The Ideal Temperature (If It Exists)

So, what is the best indoor temperature for comfort and health? According to the World Health Organization (WHO), a minimum of 18°C (64°F) is recommended for most homes to prevent cold-related health risks. Cold environments have been linked to issues like asthma, cardiovascular diseases, and even depression.

Rebecca Wilson, senior public health specialist at Public Health Wales, explains: “Healthy homes are one of the key building blocks for good health. Homes that are accessible, safe, comfortable, and warm help to protect our health and support our communities to be healthy and resilient.”

 

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At the same time, cranking up the thermostat too high has its own dangers. Overheating can increase the risk of heat exhaustion and heatstroke, especially in hotter climates. There’s also evidence that excessive warmth negatively impacts mental health, with studies linking high temperatures to increased stress and even suicide rates.

How Age and Biology Play a Role

If you’ve ever argued with an older relative over how warm their house needs to be, there’s a scientific reason for that. Elderly people typically have a lower resting body temperature and slower metabolism, meaning they struggle to generate heat efficiently. Research has found that even temperatures as low as 18°C (65°F) can lead to hypothermia in older adults.

On the flip side, babies and young children are more prone to overheating, which is why organisations like The Lullaby Trust recommend nurseries be kept between 16-20°C (60-68°F) to reduce the risk of Sudden Infant Death Syndrome (SIDS).

And then there’s the gender divide. Women often feel colder than men due to lower metabolic rates and differences in fat distribution. A study from Finland found that women were more likely to feel both too hot and too cold in office environments, making workplace thermostat settings a common source of conflict.

 

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The Thermostat Wars in Offices and Homes

It’s not just at home where temperature battles happen. In the workplace, regulations in the UK suggest a minimum of 16°C (60°F) (or 13°C (55°F) for physically demanding jobs). Meanwhile, in the US, there’s no legal requirement for heating or air conditioning, though the Occupational Safety and Health Administration (OSHA) recommends 20-24°C (68-76°F) for office environments.

These small differences can significantly impact productivity. Heat stress has been shown to reduce cognitive performance, while working in a cold office can lead to poor concentration and increased risk of illness.

 

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Why Temperature Affects Sleep

If you’ve ever struggled to sleep in a room that’s too hot, that’s because temperature plays a crucial role in sleep quality. Bill Wisden, director of the UK Dementia Research Institute at Imperial College London, explains:

“Sleep is temporally related to the circadian rhythm of core body temperature and skin temperature.”

Essentially, body temperature starts to drop a few hours before sleep, and a cooler room (16-18°C or 60-65°F) can help encourage deeper, more restful sleep. Sleeping in a room that’s too warm can cause frequent awakenings and disrupt the non-REM stage of sleep—the most restorative phase.

Wisden also notes that a hot bath before bed can help induce sleep. His research on mice found that warming the skin sends signals to the brain, triggering a cooling effect that promotes sleep.

Final Verdict: There Is No One-Size-Fits-All Temperature

With so many variables—age, gender, metabolism, and environment—it’s impossible to declare a universal “perfect” indoor temperature. Instead, the key is finding a balance that suits individual needs while preventing health risks. Whether you’re a heat-lover or a fresh-air fanatic, one thing is clear: your thermostat wars aren’t ending anytime soon.