Leaving the heating on overnight results in poorer sleep, doctor says

Our body produces more melatonin when our core temperature drops

A woman sleeping at night (Getty Images/iStockphoto)

An NHS doctor has revealed why people should not leave their heating on overnight this winter, as it will disrupt their quality of sleep.

In a video posted to TikTok, Dr Karan Rajan explained that sleeping in a cold room helps lower our core body temperature.

This is important as the level of melatonin – a hormone that increases sleep propensity – increases as our core temperature lowers.

An increased amount of melatonin also promotes anti-aging because it reduces levels of cortisol, the stress hormone, and oxidative stress damage.

“It also reduces systemic inflammation, and its free,” Rajan said.

Sleeping in a cold room may also help those who suffer from insomnia.

As the human body’s core temperature needs to drop in order to initiate sleep, “warmer temperatures mean your brain and body are more active trying to cool you down”, Rajan explained.

“A cooler temperature gets you closer to the target sleep temperature of your body, and you fall asleep a lot faster,” he added.

Additionally, increased brain activity prior to falling asleep can limit the amount of REM and slow wave sleep (SWS) the body gets – both of which it needs to recharge.

REM sleep stimulates the areas of the brain that are vital to leaning and making and retaining of memories and usually occurs in the first 90 minutes after we fall asleep. Slow wave sleep is the deepest phase of sleep.

Another benefit of sleeping in a cold room is that it may improve metabolic health.

“There is research to suggest that cold exposure can increase the amount of brown fat produced by stem cells. Brown fat helps to regulate cholesterol and improves insulin sensitivity,” Rajan said.

In 2019, a study by researchers at the University of California found that men with high levels of brown fat had reduced levels of branched chain amino acids (BCAA).

Although these compounds are essential for many functions in the body, high levels of BCAAs have been linked with obesity and insulin resistance.