Parts of the UK are bracing for a weekend of sizzling heat following days of record-breaking temperatures. Kew Gardens in London reached 35.1C on Monday, exceeding its previous station record of 29.3C and the previous UK May record of 32.8C. The Met Office said 163 stations broke their May maximum temperature records in total. Saturday will continue to deliver sunshine, with temperatures set to climb as high as 29C in England and Wales.
While intense heat can cause physical discomfort and exhaustion, it can also affect mental wellbeing and overall mood. Dr Ravi Gill, a health psychologist, explains that prolonged high temperatures can cause anger and anxiety due to physiological changes in the body and brain. “Heat disrupts neurotransmitter systems (serotonin), impairs sleep and raises stress hormones like cortisol, which are key regulators of mood and impulse control,” she says.
The physical discomfort and disrupted sleep from heatwaves can exacerbate mood instability, trigger anxiety spikes, or worsen irritability. “Lingering discomfort and environmental stress strains emotional resilience, making even minor irritants feel overwhelming,” adds Dr Gill. “Heatwaves can also escalate social tensions – whether at home, in traffic, or public spaces – turning minor triggers into conflicts.”
Research suggests that people with pre-existing mental health conditions are more vulnerable during heatwaves. Conditions such as anxiety, depression, bipolar disorder, or schizophrenia can make it harder to recognise early signs of heat stress or take action. Additionally, some psychiatric medications reduce the body’s ability to sweat or regulate temperature, increasing the risk of heat exhaustion or heatstroke.
High nighttime temperatures make it harder for the body to drop its core temperature, which is essential for deep, restorative sleep. “People wake more often, particularly during REM sleep, which is vital for emotional processing and memory consolidation,” says Dr Gill. Poor sleep lowers activity in the prefrontal cortex and heightens amygdala reactivity, making us more emotionally volatile.
Heatwaves can also impair core cognitive functions like memory, focus and decision-making. Reduced cerebral blood flow, neurotransmitter disruption and electrolyte imbalance are contributing factors. “Even mild dehydration (1-2 percent body weight loss in fluids) can slow neural processing and impair memory, attention, and reaction time,” says Dr Gill. She advises drinking water regularly, not just when thirsty, and including electrolyte sources to counter-balance these effects.
