Schools across the UK are being forced to take drastic action this week: closing at lunchtime, suspending uniform policies and cancelling school trips.

These measures are in response to the four-day amber weather warning (upgraded to a red warning in some areas for Wednesday and Thursday) for extreme heat issued by the Met Office and set to remain in place until Friday morning. Forecasts suggest that some parts of the country could see temperatures climb as high as 39C.

Unions have recently called on the government to introduce a maximum working temperature for schools, and the Department for Education has estimated that around 6.7 days of learning are being lost each year as a result of heat.

We’re all familiar with the feeling of not being able to focus properly when it’s too hot, but what exactly is going on in the brain to make overheating such a hindrance? And is there anything we can do to counteract the effects?

To understand what heatwaves do to our brains, Tes spoke to Dr Laurence Wainwright, senior departmental lecturer and course director at Smith School of Enterprise and the Environment at the University of Oxford.

How high temperatures affect learning

“The human body is very adaptable,” says Wainwright. But, he cautions, “Putting kids in a room when it’s 27C for multiple days in a row is not going to work.”

That’s because once the temperature rises above about 25C, “the whole learning process is severely disrupted. Teachers are not able to do their job properly, behaviour gets out of control and the whole thing falls apart quickly”.

Several studies have investigated the impact of heat on learning and performance, he adds, estimating a difference in students’ test performance of around 15 per cent in a 26C room versus one cooled to 18C.

So, why are our brains so negatively affected by the heat?

“Essentially, as the temperature gets hotter, the brain and body are diverting their attention to cooling down,” Wainwright explains. “The brain’s resources are limited, and it deems cooling down the highest priority. As a result, those higher-order cognitive skills really go out of the window.”

Executive function, working memory, pattern recognition and the ability to read and process information - all skills essential for the process of learning - do not work properly, Wainwright says. “So the learning cannot happen”.

Fine motor skills can also be impacted when children are writing or typing.

“The child may be able to sit still, they may be able to take out their textbook and engage in the process of reading, but the amount of information sinking in and their ability to synthesise information - to read a text and make a nuanced, articulate observation of what they just read - becomes extremely difficult.”

A 2018 study measured attention, processing and working memory (the ability to hold information in your mind while you use it to do something) for a group of students who had air conditioning in their building during a heatwave, and a group that didn’t.

Those in the group without air conditioning had longer reaction times and performed worse in tests of addition and subtraction.

Meanwhile, research in 2024 suggested extreme heat exposure elevates the temperature of the brain, disrupts motor cortical activity (related to motor function), causes reduced brain perfusion (blood flow) in some areas, and contributes to poorer executive function (mental skills such as working memory, attention control and inhibition control).

So, the effects are widespread. For teachers, this means “they’re really fighting a losing battle from the onset,” Wainwright says.

“If we think about the process of a teacher disseminating information to students, they’re learning new concepts, then applying the concept and saying, ‘How does it work in practice?’, and then, at the highest order, stepping back and critiquing the concept and being able to think critically about it.

“The second and third steps are not really possible in a very hot room,” he continues. “You might have the teacher being able to teach foundational concepts and explain a new concept, but it’s not really sinking in. And if we then try to apply that skill, it becomes very difficult.”

But the problems go beyond learning, he adds. Extreme heat is associated with a rise in aggression and emotional regulation, and evidence has shown that behaviour in the classroom worsens when the temperature exceeds 25C.

Teaching in the heat

This all happens via a complex range of mechanisms that are also impacted by the age of the person in question, pre-existing health conditions, mental health conditions, medications and socioeconomic factors, Wainwright says.

Children are more vulnerable than adults, but teachers will feel the effects, too.

“The ability to explain complex phenomena, engage in quick back-and-forth with students and pick up subtleties in the room will all be impacted. It may also be that teachers find they lose their temper more easily,” he says.

So, can anything be done to overcome these effects?

The best solution in the short term is to bring the temperature of the room down - through the use of air conditioning, for example. In the long term, school buildings will need to be designed with sustainable cooling methods in mind.

However, very few state schools have air conditioning - to the point where some are considering options to raise the cash needed for other methods of cooling. Belmont Junior School, a maintained school in Haringey, London, which has recently seen classroom temperatures hit 32C in summer, is running a fundraiser to enable it to plant more trees, install external blinds and replace heat-absorbing tarmac.

The sleep factor

Even if we manage to cool down our classrooms, another impact of prolonged hot weather that most of us in the UK are familiar with is the disruption of sleep in our heat-trapping houses, where temperatures tend to climb higher and higher the longer a heatwave goes on.

Children coming to school without having had enough good-quality sleep will already be experiencing impaired impulse control and capacity for learning, Wainwright says - and hot temperatures in lessons will only exacerbate those problems.

All pupils will feel the effects, but for those sitting exams, the cognitive challenges might feel particularly pronounced, he adds.

“Doing A levels and GCSEs at the peak of summer when there’s a heatwave - that’s pretty serious,” Wainwright says.

And with no way to help those students beyond cooling the exam hall down, he says, “I think we need to get serious about air conditioning in this country - particularly around exam periods.”