On oppressively hot days, Hayes finds it hard to function at work and complete daily tasks. They become irritable and say their anxiety “goes through the roof”.

Hayes says their mental health suffers when the weather heats up. Credit: Supplied

“During the hotter months, my mental health goes downhill in multiple ways and I start to just have symptoms of depression as well as dissociation symptoms because the heat is so much.

Hayes says they’re privileged in the sense that they have access to air conditioning and relatively cool spaces in their home. Still, when the temperature rises, Hayes says it can be an isolating and frustrating experience — particularly because they can’t drive a car.

“I struggle to get out of bed even some days because it’s just so much energy.”

• This is part three of a three-part series exploring the adverse impacts of climate change on mental health and wellbeing.  and

The problem with heat

When temperatures rise, so does aggression, domestic violence, issues associated with mental and behavioural disorders — including self-harm — and mental health emergency presentations and hospital admissions.

Dr Cybele Dey, a child and adolescent psychiatrist from the University of NSW, says the role of heat in exacerbating mental health issues is under-discussed considering “how widespread heat is and how many people are being impacted by it”.

Emergency department mental health presentations go up during heatwaves. Source: AAP / Paul Miller

Heatwaves cause hundreds of hospitalisations every year in Australia and are considered the most dangerous natural hazard in terms of loss of life. Dey says that in addition to the physical health risks associated with heat, mental health risks need to be taken more seriously, and greater resources allocated.

In her work as a psychiatrist, Dey says she has seen the extra pressures placed on the public health system as heat increases.

One study led by Dey found youth suicidality presentations in NSW appear to increase by 1.3 per cent for every 1C rise above average daily mean temperature.

Extremely hot days can lead to increased isolation, as more people stay in their homes to avoid high temperatures. Source: Getty / bymuratdeniz

The same connection has been found in international studies. One 2023 study from New York City looked at more than 82,000 youth mental health emergencies between June and August and found hotter days were associated with a higher risk of mental health-related emergency department visits.

Adults are also susceptible to the mental health effects of heat. Dr Lucas Hertzog, a sociologist from Curtin University, says the stress of heat “interacts with the social realities” a person is already experiencing.

Hertzog led a study published last year that looked at the number of suicides in Australia that could be attributed to climate change-induced heat.

The authors found that from 2000 to 2019, approximately 0.5 per cent (or 264 suicides) could be attributed to anomalous hot days caused by climate change.

The people most vulnerable to heat

One 2021 study of mental-health-related emergency department visits in the US found an 8 per cent increase on the hottest days of summer among people living with mental health conditions, which ranged up to 11 per cent for certain diagnoses.

Dey says the impacts of heat are often worse for those who are affected in multiple ways.

“My experience over the last couple of years is getting worse and worse,” she says.

“Emotionally, it’s like just being let down and isolated and feeling like I’m in this alone.”

Dr Cybele Dey says that cities need to adapt to provide better shelter so people can continue to move freely, even on extremely hot days. Source: AAP / Steven Markham

Fighting heat for mental wellbeing

However, both Dey and Hertzog agree that climate action is the key political force needed to combat this growing problem.

“But we can make a difference to how much worse that gets by a rapid transition off fossil fuels, now.”