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Should you leave the heating on overnight when it's very cold?

Hannah Millington and Kate Ng

Updated February 7, 2025 at 7:55 a.m.

Woman sleeping, representing whether to leave heating on or not. (Getty Images) — It's tempting to keep the heating on low when temperatures plummet overnight - but is that advised? (Getty Images)

Britons have been warned of an incoming cold snap, with temperatures expected to plunge to -7C in some parts of the country overnight.

Due to the freezing temperatures, the UK Health Security Agency (UKHSA) also issued several amber Cold Weather Health Alerts.

The UKHSA issues the alerts when very cold temperatures have the potential to impact health and wellbeing, especially those who are elderly or have health conditions.

With that in mind, many of us will be wondering whether we should leave the heating on overnight during colder conditions. Here's what you need to know.

Horizontal close-up view of woman hand touching heat radiator temperature at home with white background — It's important to keep rooms warm during the cold weather alert. (Getty Images)

Should you leave the heating on overnight when the temperature drops?

When deciding whether to leave the heating on at night time, it's useful to know what temperature experts advise your home should be in winter.

The Energy Saving Trust states the thermostat in your home should be set to the lowest comfortable temperature (usually between 18C and 21C), while an official report also outlines 18C as the recommended minimum. The vulnerable may wish to heat it slightly higher, and healthy people may wish to heat it slightly less.

And this is similar for overnight.

"It is widely accepted by sleep experts that the ideal temperature for sleep is approximately 18.3C, although we also know this varies slightly person to person," says Nuffield Health physiology national lead, Louise Wright.

"For those over 65 or with pre-existing medical conditions, a systematic review by Public Health England in 2014 stated that maintaining the 18C threshold overnight may be beneficial to protect health, alongside the use of sufficient bedding, clothing and thermal blankets or heating aids as appropriate."

For babies, The Lullably Trust advises that a room temperature of 16-20C – with light bedding or a lightweight, well-fitting baby sleep bag – is comfortable and safe overnight.

A young woman in a warm hat and sweater lifts a sleeping mask while in bed. (Getty Images) — If you're fighting fit the heating may not be needed overnight, as long as you wrap up warm. (Getty Images)

How does the temperature at night affect your health?

Being too hot, or too cold, will disrupt your body's ability to get a good night's sleep and keep you healthy.

"A person's core body temperature is regulated by the circadian rhythm," explains Wright. "This means, like our hormones, it rises and falls over a 24 hour period. At night the core body temperature should drop slightly, coinciding with the release of the sleep hormone melatonin, and this signals that the body is preparing and ready for sleep.

"The body starts to cool itself through the process of vasodilation, allowing the blood flow to move away from the core towards the extremities (and this is why you sometimes experience hot feet and hands at night!)."

But, Wright adds, "If where you are sleeping is too warm however, this can interfere with your body’s thermoregulation and therefore cause discomfort and restlessness, as well as a decreased amount of time spent in the restorative stage of sleep."

Overall, it's generally thought to be better to be too cold, than too hot, while trying to sleep, but as you obviously don't want to suffer the implications of shivering through the night, consider whether it's important for you individually to keep your bedroom heated to the 18C minimum, or whether you can stay warm in other ways.