Children mental health hospital visits rise with extreme heat, study finds

Mental health hospital admissions among children and young people increase during periods of high temperatures, a new study has found. As global temperatures have been rising at an accelerating pace, their impact on health is expected to intensify correspondingly, authors warned.

Extreme heat raises the risk of several mental health conditions, from substance use and depression to anxiety, obsessive-compulsive disorder and behavioural disorders, according to the study by the University of Sydney in Australia.

"Hotter-than-normal weather, which is becoming more frequent because of climate change, is already affecting the mental health of some of our most vulnerable young people," said lead author Wen-Qiang He.

One in seven 10-19-year-olds worldwide experiences a mental disorder, accounting for 15% of the global burden of disease in this age group, according to the World Health Organization.

A burden projected to worsen due to climate change, Wen-Qiang He warned, adding that mental health is an increasingly important consideration in climate adaptation and public health planning.

By 2090–2099, heat-attributable admissions are projected to rise between 6.0% and 7.7% under a low or moderate greenhouse gas emissions scenario and by 20.8% in a high emission scenario.

The researchers analysed data from all mental health hospital admissions among children up to 12 years old and adolescents from 13 to 17 years in New South Wales — Australia’s most populous state — between 2001 and 2022.

They found that hospital admissions rose during hotter days, especially during the cold season.

While the reason for the higher number of mental health visits remains unclear, the researchers suggested that unexpected temperature changes may influence stress responses, sleep and mood.

How does heat affect mental health?

The study notes that high temperatures make it harder for the body to regulate its internal temperature, affecting cell function, inflammation, blood pressure, and the brain's cooling and oxygen supply.

It can also trigger mental stress, impair sleep, and contribute to irritability, aggression and violence.

Elevated temperatures can also have an indirect effect on health, reducing sleep quality and social interaction.

With temperatures set to intensify due to climate change, the study authors call for better prevention and adaptation strategies tailored to children and young people with mental health conditions.

These include providing access to air-conditioned rooms in schools, community centres, and youth services, adjusting school schedules to reduce outdoor activity during peak heat, and specifically including mental health in public heat warnings.