Why am I so Irritable in a Heatwave?: The Psychology of Hot Weather
- 1 day ago
- 5 min read
For a country that spends most of the year talking about rain, the UK certainly has a lot to say when the temperature suddenly shoots up. One minute we're celebrating blue skies and eating ice cream in the garden, the next we're struggling to sleep, snapping at our friends, and wondering why making a cup of tea feels like such hard work.
If you've felt unusually tired, forgetful or irritable during a heatwave, you're not imagining it. While a lovely, sunny day can be amazing for our mental health, extreme heat has a big effect on how our brains work.
Heat and energy
Our brains are extremely energy-hungry. At around 1.2kg, your brain makes up about 2% of your body weight, but uses around 20% of the calories your body burns every day. Most of the time, your body and brain work together well, distributing resources fairly. However, when the weather is hot, your body has a new important priority: preventing you from overheating.
To cool itself down, your body sends more blood to your skin so that heat can escape, and produces more sweat. All of this takes energy and water. As a result, your brain has to compete with the rest of your body for resources, which can leave you feeling mentally sluggish. [1]
How hot weather affects attention and memory
Many people notice that concentrating becomes harder in hot weather. You might find yourself reading the same sentence three times, forgetting why you walked into a room, or making simple mistakes at work or school.
Researchers have found that high temperatures can reduce your attention span, affect your working memory (holding things in your head while you’re doing them) and executive function (things like decision-making and problem solving). [2] With so much of your body’s resources dedicated to keeping you cool, this leaves less energy for those higher-order mental functions. So it’s not that the hot weather is making you less intelligent, it’s your body trying to survive in extreme conditions!
Why does heat make us grumpy?
If you've ever found yourself getting disproportionately annoyed because someone chewed too loudly or took too long at the supermarket checkout during a heatwave, there's science behind that, too.
Being hot is physically uncomfortable. Your brain has to constantly monitor your internal temperature, and when it detects you're getting too warm, it treats this as a source of stress. Stress makes us less patient and more emotionally reactive. [3]
There's also the sleep problem. Warm nights make it much harder to fall asleep and stay asleep, because our bodies need to cool down as part of the falling-asleep process. Even one poor night's sleep can leave us feeling irritable, less resilient and less able to regulate our emotions the following day. Add several hot nights together, and it's no wonder tempers can become a little frayed. [4]
Dehydration doesn't help either. Even mild dehydration can affect our mood, increase fatigue and make it harder to think clearly. If you’re hitting an afternoon slump where all you want to do is lie down and whimper, grab a glass of water, as you may just be a little dehydrated.
It's also important to be aware that certain medications, including antidepressants like SSRIs and SNRIs, can affect our body's heat responses, making us more susceptible to extreme heat. [5] If you're on any regular medication, check the label and make sure you're being extra-vigilant about drinking water.
Why children struggle with heat
Heat affects children's brains and behaviour in many of the same ways, but they often show it differently.
Young children may become unusually clingy, emotional or prone to tantrums. This is because young children’s natural response to stress is to look to their caregiver for support and reassurance. Babies and younger children are also less able to regulate their body temperature than adults, making them more vulnerable to overheating.
School-aged children might seem restless, struggle to concentrate or become frustrated more easily. Add to that the fact that most UK schools are built to trap heat, not dispel it, and teachers may notice a drop in attention spans and an increase in bad moods in their classrooms. [6]
Children may not recognise that they're thirsty or overheating until they're already uncomfortable, so adults play an important role in spotting the signs. It's also worth remembering that younger children often struggle to explain that they're simply too hot. They may just seem out of sorts.
Plan energetic activities for the cooler parts of the day, and build in plenty of calm indoor time during the hottest hours. Water play, reading, drawing or listening to stories can all help children stay entertained without overheating. Offer regular drinks without waiting for children to ask, and encourage them to take breaks if they're becoming flushed or tired.
Looking after your brain in hot weather
With so many negative effects of heat, it’s important to do your best to look after your brain during a heatwave. Here are a few simple steps:
Stay hydrated
Drink water regularly throughout the day, rather than waiting until you feel thirsty. Carry a water bottle with you if you go outside, and take small, regular sips to keep your body hydrated. Foods with a high water content, such as watermelon, cucumber and strawberries, can help too.
Prioritise sleep
Sleep is extra important when it's hot. Keep bedrooms as cool as possible by closing curtains during the day and opening windows when it's cooler outside. Lightweight bedding and a shower before bed may also help.
Lower your body temperature
While taking a freezing cold shower may seem appealing, it actually causes your body to heat back up afterwards. Instead, taking a lukewarm shower helps to lower your body temperature and keep it low. Tricks like wrapping an ice pack in a towel and putting it between your legs or under your arms (next to major arteries) can also help.
Lower your expectations
Your brain isn't operating under ideal conditions. If you're finding it harder to concentrate or feeling less productive than usual, that's completely normal. When temperatures soar, it might not be the best day to tackle the most mentally demanding task on your to-do list… and that’s ok!
Be patient with yourself and others
Remember that everyone else is dealing with the same physiological and psychological stress. If family members seem a little shorter-tempered than usual, children are struggling to focus or settle in the classroom, or coworkers are making more small mistakes in their work, the heat may be playing a bigger role than you realise.
The psychology of heat reminds us how closely our minds and bodies are connected. Feeling irritable, tired or forgetful during a heatwave isn't a personal failing, it's your brain responding to genuine physical stress.
So if you find yourself losing your train of thought, feeling less patient than usual, or wondering why everyone seems a bit grumpy, remember that your brain is working overtime to keep you safe.
[6] https://www.som360.org/en/blog/how-heat-waves-affect-emotional-well-being-children-and-adolescents
