This is what the warmer weather is doing to your brain function
Heat can affect your mood and brain in many ways, from mild symptoms, like sluggishness or irritability, to more extreme problems.
It’s time to dig out that bottle of sun cream from the depths of your bathroom cabinet, as the UK’s spell of sunshine is set to stick around this week.
Monday was hottest day of the year so far – with 24.5°C recorded in St James’s Park, London – and meteorologist Jonathan Vautrey told PA news agency that temperatures would push towards 25°C in the South East and London on Tuesday, with highs of 27°C expected on Wednesday.
With the rising temperatures, we are curious about how the heat might influence our brain function. So, we got in touch with Dr Steven Allder, a consultant neurologist at Re:Cognition Health to explore how warmer weather can impact everything from memory and concentration to emotional stability.
What are the known effects of heat on cognitive performance, such as memory, focus and decision-making?
“Heat can impair several areas of cognitive performance, including attention, short-term memory and decision-making,” says Allder. “When the body overheats, resources are diverted from the brain to regulate core temperature, which can slow processing speed and reduce mental clarity.
“People may find it harder to concentrate, solve problems or retain information. This is especially noticeable during prolonged heat exposure or dehydration, which further affects neural efficiency.”
Can hotter temperatures impact emotional instability?
“There is growing evidence linking hotter temperatures to emotional instability,” says Allder. “Elevated heat levels have been associated with increased irritability, frustration and even aggression.
“This may be due to disrupted sleep, discomfort, or heightened stress responses. The brain’s emotional regulation centres, particularly the amygdala, may become more reactive in extreme heat.”
Can heat contribute to mental fatigue?
Heat can significantly contribute to mental fatigue.
“When the body is trying to cool itself, more energy is used for thermoregulation, leaving fewer resources available for cognitive functioning,” explains Allder. “This can result in feelings of tiredness, mental sluggishness and reduced alertness. Tasks that require concentration or decision-making become more difficult and motivation may drop.
“Mental fatigue during heat exposure is particularly common when hydration is inadequate or when individuals are exposed to prolonged periods of warmth without adequate rest or cooling.”
Does warm weather have any positive impacts on our brain?
Warm weather can have positive effects on the brain, particularly through increased exposure to sunlight.
“Sunlight stimulates the production of serotonin, which helps improve mood, sleep, and overall emotional balance,” says Allder. “Higher vitamin D levels, often resulting from sun exposure, are also linked to improved cognitive function and mental health.
“People tend to be more active and socially engaged during warm weather, which benefits brain health. However, these advantages are most apparent when temperatures remain comfortable and not excessively hot.”
Are people with neurological condition more vulnerable to heat-related changes?
People with neurological conditions such as multiple sclerosis (MS), epilepsy and migraines are more susceptible to heat-related symptoms.
“In MS, even small increases in temperature can worsen fatigue and impair nerve conduction,” notes Allder. “For those with epilepsy, heat and dehydration may lower seizure thresholds. Migraines can be triggered or intensified by high temperatures and changes in atmospheric pressure.
“These individuals need to take particular care in hot weather, as their conditions make it harder for the nervous system to tolerate thermal stress.”
What long-term neurological effects might be associated with chronic exposure to high temperatures?
“Prolonged heat stress can contribute to systemic inflammation, oxidative stress and vascular dysfunction, all of which can negatively affect the brain,” says Allder. “Over time, this could increase the risk of cognitive decline, poor sleep, and potentially neurodegenerative diseases.
“Repeated dehydration episodes may also impair brain structure and function.”
Are there any adaptive mechanisms the brain uses over time to cope with frequent heat exposure?
“The brain and body can gradually adapt to frequent heat exposure through a process known as heat acclimatisation,” explains Allder. “Over time, the body becomes more efficient at regulating temperature by improving sweat response, blood flow and cardiovascular efficiency.
“While these changes help protect the brain from overheating, they may not fully prevent cognitive or emotional strain.
“The degree of adaptation varies between individuals and depends on factors such as age, fitness, and underlying health conditions.”
Is there anything we can do to protect our brain health in hot weather?
“Staying well-hydrated is essential, as even mild dehydration can impair cognitive function,” highlights Allder. “Limiting time outdoors during peak heat hours, wearing light clothing and using fans or air conditioning can help maintain a safe body temperature.
“Eating light meals, taking regular rest breaks and ensuring good sleep hygiene are also beneficial. Those with neurological conditions should also take extra precautions and may benefit from personalised advice from their healthcare providers.”