Slower than usual? The warm weather is affecting your brain

Metro

01-05-2025

Feeling sluggish? You're not alone.
The UK has been basking in high temperatures, with some parts of the country set to reach 29C.
But, as we all flock to beer gardens to enjoy the mini heatwave, our brains could be struggling to cope.
It all comes down to our own body temperature, and how hard the brain works to regulate it.
'The temperature that the body needs to stay within is an unbelievably narrow window,' consultant neurologist, Dr Steve Allder, tells Metro.
'If your temperature rises from 37C to 41C there's a very good chance that it would kill you. Similarly, if it dropped from 37C to 33C, you would really start to struggle.
'The body really has to work hard to keep our temperature in a tight range, especially in hot weather, and that then takes energy away from the brain.'
A&E doctor, Dr Mark Cox tells Metro: 'When you're hot, your body is in a constant state of thermoregulation (keeping your temperature stable).
'This burns energy and diverts blood flow toward the skin to release heat, which means less energy and oxygen get to your brain.'
So, now we know the science – what does that mean for how you feel?
'You'll notice it in things like memory lapses, poor concentration and slower decision-making,' Dr Mark says.
And while we all might find ourselves getting a bit, well, aggy, in hot weather, Dr Mark says that's to do with your brain too.
Dr Sameer Sanghvi, GP at Lloyds Pharmacy Online Doctor, warns that hot weather can be particularly dangerous for people taking antidepressants.
He explains: 'Common antidepressants can all stop the temperature-regulating area of the brain from functioning as it should. Serotonin-noradrenaline reuptake inhibitors(SNRIS) and selective serotonin reuptake inhibitors (SSRIS) are some of the most commonly prescribed antidepressants.'
If you are prescribed these antidepressants, Dr Sanghvi warns not to suddenly stop taking them. 'You should always consult your doctor before making changes to your mental health medication,' he adds.
'The best thing you can do is take precautions to stay cool: stick to the shade; drink plenty of fluids and avoid alcohol.'
'Heat can amplify reactivity in the brain's emotion centre, the amygdala, and reduce the calming influence of the parasympathetic nervous system,' says Dr Mark, co-founder of Orli Health. More Trending
'That makes people more prone to irritability, impulsiveness and even aggression.'
For those with existing neurological conditions, warm weather can cause these symptoms to worsen.
Dr Steve, who works at Re: Cognition, says that those with multiple sclerosis, for example, 'will have far less resilience' to cope with temperature changes.
He adds: 'This is also true for something like migraines. People find that they get more migraines when it gets hot.'
If your body can't cool itself down, you risk developing heat exhaustion, which could progress to heat stroke if left untreated, a life-threatening condition.
Dr Allder says that those doing prolonged exercise in the sun should be careful of developing heat stroke, especially if they're not taking in enough fluids. He adds: 'Make sure to stop if you feel lightheaded or woozy.'
To protect yourself from the temperature changes, Dr Allder advises avoiding the sun, hydrating and resting.
Most adults should aim to drink at least six to eight glasses a day (around 1.5-2 litres), but Dr Allder advises getting an extra 500ml to 1 litre per day.
According to the NHS, the signs of heat exhaustion include: Weakness
Tiredness
Dizziness
Headache
Feeling sick or being sick
Excessive sweating and skin becoming pale and clammy, or getting a rash
Cramps in the arms, legs and stomach
Fast breathing or heartbeat
A high temperature
Being very thirsty
If someone is showing signs of heat exhaustion, they need to be cooled won and given fluids, the NHS website says.
Heat exhaustion does not usually need medical help if you can cool down within 30 minutes. However, if it turns into heatstroke, it needs to be treated as an emergency.
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