New issue: Brain-melting heat

As I write this, it’s stupid hot. I mean that literally: it’s so hot that it’s difficult to think. My thoughts feel as though they’ve been wrapped in cotton wool and then set on fire. As it turns out, though, the way I feel isn’t that far removed from what’s happening inside my brain. Nothing is actually burning between my ears, but heat can interfere with the millions of tiny electrochemical interactions that my – and your – neurons rely on to function. Brain cells have a temperature range in which they work at their best, but push the temperature too high and some of the molecular machinery involved in sending signals becomes less reliable. It’s a little like an orchestra losing its conductor: the instruments are still there, but the timing starts to fall apart. Taken to extremes, this is why heatstroke can cause confusion, dizziness and other changes in brain function. And the heat doesn’t only affect the brain directly. As my body heats up, my circulatory system sends more blood towards my skin to help me lose heat, making my heart work harder. Sweating also means losing water and salts, and as dehydration sets in, maintaining a normal blood supply becomes more difficult – adding another challenge for a brain that’s already under thermal stress. Sweat and aggravation are, of course, far from the worst consequences of extreme heat. But this year, the soaring temperatures have felt relentless. Wave after wave of heat has battered Europe and the US, with barely enough respite before the next one arrives. We’re going to have to adapt. We can change our buildings, routines and behaviour to make extreme heat easier to bear. But what happens to the organ that controls all those decisions when the temperature keeps rising? In this issue, we're exploring what heat does to the brain – from our ability to think clearly and make decisions, to our mood, sleep and mental wellbeing. And because knowing it’s too hot doesn’t make it any cooler, we've also found some scientifically proven advice on the fastest way to cool down.

Holly Spanner

Published: August 20, 2026 at 7:00 am

The front cover of issue 436 of BBC Science Focus magazine

How to spot a liar

There are ways to spot when someone is trying to deceive you. But you have to listen carefully to what they’re saying. Here are five tells to look out for, with studies taken from real criminal trials.

Prediabetes

If you've recently been diagnosed with prediabetes, it could be a blessing in disguise. With the right diet and lifestyle changes, there are ways to reverse the slide towards type 2 diabetes, but doing so means acting on the early warning signs.

The mysterious deep

We’re getting our first glimpses at the strange lifeforms that are lurking beneath the Antarctic – and they’re nothing like what we expected. What sort of life has evolved after a million years in isolated darkness, with crushing pressure from the water above?

'Godzilla Ozempic'

A new weight-loss drug has arrived. And it’s far more powerful than anything that came before.

Plus

Killer droids: The terrifying, unmanned ground and air vehicles that are changing modern warfare as we know it. Is this the future of war?
Dark DNA: Scientists are starting to decode parts of the human genome previously dismissed as junk. But these mysterious sequences could fundamentally alter our understanding of biology, and geneticists are racing to uncover their true purpose...
Q&A: Your questions answered by our team of experts. This month: What animals are best at puzzles? How long can you do nothing for? Why do I have visual snow? How does coffee change my gut? Why do we keep smallpox in a lab? Should I drink still or sparkling water? Should I be worried about my teenager’s moods? And more…

Issue 436 on sale Thursday 20 August 2026

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Staff Writer, BBC Science Focus

Holly is the Staff Writer for BBC Science Focus and looks after the popular Q&A section. She holds an MSc (distinction) in Geoscience (Space and Climate Physics) from UCL, and specialises in astronomy and earth sciences. Before joining Our Media, she worked as a geoenvironmental consultant and engineer, informing on ground risk and remediation in the north of England, while hunting for exoplanets in her spare time. Alongside this, she was regional editor of a popular theatre website for nine years, and has a solid background in curating and developing content for the digital space. Holly is also an artist and illustrator, and regular contributor to the craft website, Gathered. She has previously worked with the RSPB, English Heritage, Disney, Pilot and Brother, as well as on BBC Good Food magazine, Home Style magazine, and Papercraft inspirations magazine. She enjoys photography and has a sustained interest in antiques.

Issue 436 of BBC Science Focus is on sale from 20 August 2026