European heatwaves drive rise in aggression and mental health strain
Rising temperatures across Europe are increasing rates of violence, road rage and emergency room visits as heat stress directly impairs brain function.
Extreme heatwaves across Europe are triggering a measurable rise in aggression, road rage and emergency room visits for mental health concerns, placing a strain on public services. “Research shows that on hotter days, rates of aggression, road rage, violence, and even emergency room visits for mental health concerns tend to increase,” said Susan Albers, a clinical psychologist at the Cleveland Clinic.
This behavioural shift carries significant implications for workplace safety and public order. When the brain works overtime under heat stress to cool the body, it diverts cognitive resources away from the functions that keep people calm and focused. “When we're physically uncomfortable, we have less patience, we're more irritable, and we're quicker to react emotionally,” Albers explained.
Dehydration further compounds these risks to daily functioning. The World Health Organization recommends drinking at least two to three litres of water per day, or roughly one cup per hour, to maintain temperature regulation. Failing to do so can impair the brain rapidly. “Even mild dehydration can affect the parts of the brain responsible for attention, decision-making, and emotion. You may feel more anxious, foggy, or irritable before you even realize you're thirsty,” Albers noted.
Disrupted sleep compounds the stress
The inability to recover overnight is a critical factor. Tropical nights, where temperatures do not fall below 20°C, are becoming more frequent even in traditionally cooler European countries. During sleep, the core temperature drops and the cardiovascular system rests, allowing the body to ease the cumulative stress of a hot day, according to Armel Castellan, extreme heat services technical advisor at the World Meteorological Organization and the WHO. When nighttime temperatures remain high, this recovery process simply fails to happen. “Even one bad night's sleep can make you more emotionally reactive, impatient, and less able to cope with everyday frustrations,” said Sanders.
Medications increase vulnerability
Europeans with pre-existing mental health conditions face heightened risks during these periods. Previous research indicates heat can have both immediate and lagged effects, increasing the risk of suicide, schizophrenia symptoms, anxiety, depressive and substance use disorders. For those with anxiety, the physical sensations of overheating—like a racing heart and shortness of breath—closely mimic anxiety symptoms. “People with anxiety may notice the heat more because many of the physical sensations of being overheated like a racing heart, sweating, and shortness of breath, feel similar to anxiety, which can create a cycle where each makes the other worse,” said Albers.
Furthermore, common medications, including some antidepressants, stimulants, antihistamines and blood pressure drugs, can impair the body's ability to cool itself or increase dehydration risks. Some treatments may also become less effective or carry higher risks of side effects when a patient is overheated.
