The UK is bracing for its hottest day on record, with temperatures expected to pass 40ºC in parts of southern England.

The heatwave has left people desperately searching for ways to cool down, from putting up foil in their windows to turning wheelie bins into makeshift ice baths.

One theory you have probably heard before is that hot drinks can actually help cool you down.

And while sipping on a mug of boiling tea might not feel logical – or particularly pleasant – if it works then maybe it’s worth a try?

Here is the science behind it.

A study by researchers from the University of Ottawa looked into the effect hot drinks have on body temperature, and the limited found they can in fact cool you down in the heat – but only in certain conditions.

Dr Ollie Jay, one of the authors of the study, told Smithsonian Magazine: “If you drink a hot drink, it does result in a lower amount of heat stored inside your body, provided the additional sweat that’s produced when you drink the hot drink can evaporate.”

While sweating may be unpleasant, it is a vital mechanism the body uses to cool down.

When sweat evaporates from your skin it releases energy from your body into the air, cooling you down.

“What we found is that when you ingest a hot drink, you actually have a disproportionate increase in the amount that you sweat,” Dr Jay said.

“Yes, the hot drink is hotter than your body temperature, so you are adding heat to the body, but the amount that you increase your sweating by – if that can all evaporate – more than compensates for the the added heat to the body from the fluid.”

This means drinking a hot drink could work in dry conditions which allow the sweat to fully evaporate. If it is too humid you will simply warm up even more.

“On a very hot and humid day, if you’re wearing a lot of clothing, or if you’re having so much sweat that it starts to drip on the ground and doesn’t evaporate from the skin’s surface, then drinking a hot drink is a bad thing,” Dr Jay explained.

The study was enacted by testing cyclists in a lab, attached to skin temperature sensors, and oxygen and carbon dioxide monitors, indicating how much heat was being produced by the body’s metabolism.

Those that drank hot water stored less heat in their bodies than those that didn’t.

However, this study was very small. It featured just nine people – all men – who were constantly performing light exercise in 24ºC heat.

This means it may not necessarily translate to people sitting at a desk, fully clothed, in higher temperatures.

Stuart Ritchie, who runs the blog Science Fictions, wrote: “These studies aren’t aimed at testing whether drinking a cup of tea will cool the average person down on a hot day. They’re sports-science studies, aimed at understanding what athletes should do to maintain or improve their performance, or get the edge over rivals.

“This research is not saying that athletes should be running along chugging Earl Grey from their Thermos flask. It’s just that drinking icy water isn’t necessarily optimal for cooling under all conditions.

“It’s also not clear whether the average person – or indeed an athlete – would even notice the effect: there’s no measure of subjective feelings of coolness or comfort in the studies.”

In conclusion, there does not appear to be enough evidence to suggest necking tea on a hot day will cool you down any better than a glass of iced water, and if comfort is your goal, the iced drink is likely to provide more short-term relief.

Here are some tips for aiding sleep during the heatwave:

And here are some things you should avoid:

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