Ireland has been hit by a slew of hot and humid days over the past week, offering a final splutter of summery weather after a mostly dull and wet few months.

As much as we may lap up the sunshine and long for an Indian summer, extreme heat can take its toll on the body.

It's not just Ireland experiencing warmer weather. Temperatures in different parts of England could rise to 32C by the end of the week, and Wales and parts of Scotland are also set to experience these the hot weather conditions and "unseasonably high temperatures".

We all know extreme weather changes and heat can impact how we feel. But, what does a heatwave actually do to your brain?

What’s going on in the brain?

Woman sitting outdoors at a cafe on a hot day, looking down and tired
(Alamy/PA)

Whether we know it or not, extreme heat has an impact on how our brain functions.

"The brain is highly sensitive to changes in temperature, as its optimal functioning relies on a stable internal environment. Elevated temperatures during heatwaves can disrupt this balance and lead to a range of physiological and neurological effects," said Ella McCrystal, lead psychotherapist, clinical hypnotherapist and owner of The Northampton Clinic.

"Heat stress triggers the release of stress hormones like cortisol, which can impact mood regulation and exacerbate symptoms of anxiety and depression. Furthermore, excessive heat can impair the blood-brain barrier, potentially allowing harmful substances to enter the brain and contribute to cognitive decline."

How does heat change the brain?
There are various ways our brain can respond to heatwaves.

"Neuroinflammation and oxidative stress are two mechanisms that play a significant role in the brain’s response to heatwaves. Elevated temperatures can lead to an increase in inflammatory molecules in the brain, contributing to neuroinflammation," McCrystal explained.

"This can result in the activation of immune cells that produce harmful compounds and further damage brain cells. Oxidative stress, which occurs when there’s an imbalance between antioxidants and reactive oxygen species, can accelerate neuronal damage and contribute to cognitive decline."

What happens to cognitive functions?

For McCrystal, one of the most concerning consequences of heatwaves on the brain is cognitive impairment.

"Research suggests that prolonged exposure to high temperatures can lead to a decline in cognitive function, particularly affecting attention, memory, and decision-making abilities," she said. "Heat-induced cognitive impairment is thought to result from the reduced availability of oxygen to brain cells and the disruption of neurotransmitter systems crucial for cognitive processes."

Can extreme heat lower our moods?

Man sitting at home on a sofa during heatwave, fanning himself
(Alamy/PA)

There could be links with emotional and psychological wellbeing, too.

"Heatwaves can take a toll on mental health by intensifying pre-existing psychological conditions and triggering new symptoms," McCrystal added. "Individuals with anxiety disorders may experience heightened levels of anxiety during heatwaves, due to the physiological response to stress.

"Moreover, the discomfort and sleep disturbances caused by excessive heat can exacerbate mood disorders such as depression. Vulnerable populations, such as the elderly and those with pre-existing mental health conditions, are especially at risk."

How can you protect your brain?

McCrystal’s first suggestion is to ensure you stay well hydrated. "Adequate hydration is essential to maintain brain function," she explained. "Drink plenty of water and avoid excessive caffeine and alcohol consumption, which can contribute to dehydration. Seek out air-conditioned spaces to escape the heat and regulate body temperature. Keeping the living space cool can help prevent the adverse effects of heat stress on brain health.

"Engage in relaxation techniques, deep breathing, and mindfulness practices to manage stress and anxiety exacerbated by heatwaves. [And] check on elderly relatives, neighbours, and individuals with pre-existing mental health conditions to ensure their wellbeing during heatwaves," she added.

"By adopting protective measures and raising awareness about the potential risks, we can mitigate the impact of heatwaves on brain health and promote overall wellbeing in the face of changing climate patterns."