Hot weather has been linked to an increase in suicidal thoughts and behaviours among young Australians, new research shows, prompting calls for an overhaul of public health approaches to higher temperatures.
The number of young people in NSW presenting to hospitals for suicidal thoughts and behaviours rises with the temperature, a new analysis of emergency department (ED) presentations shows.
Researchers studied more than 55,000 suicidality presentations made by young people, aged 12 to 24, at EDs during the warmer months of November to March, from 2012 to 2019.
The analysis, published in the Australian & New Zealand Journal of Psychiatry on Thursday, found youth ED visits for suicidal thoughts or behaviours increased by 1.3% for every 1°C rise in daily mean temperature (DMT).
The increases occurred across a full range of temperatures and on single hot days, not only during heatwaves when factors like poor sleep were more likely to be an issue, said lead author Dr Cybele Dey, a psychiatrist and conjoint lecturer at UNSW Sydney.
“The impact on the very first day where the temperature is hotter than usual is just as bad as each subsequent day, and the effect starts at a more moderate temperature than expected,” said Dr Dey.
“This is not about concern about climate change affecting the mental health of young people, this is about hot weather itself affecting them.”
For example, on days with a 24-hour DMT of 21.9°C – the average for the study period – there was an average of 45.7 youth suicidality presentations statewide. At that level presentations were already 4.7% higher than they would be at a DMT of 18.3 °C, the state’s average for spring.
By a DMT of 25.2°C, the base for a heatwave, presentations were about 9% higher than at the spring DMT, and about 15% higher by a DMT of 30°C, which is reflective of extreme heat. There were 94 heatwave days over the study period.
The researchers, from UNSW, Sydney Children’s Hospitals Network, NSW Ministry of Health, NSW Health, The University of Sydney and Queensland Children’s Hospital, controlled for long-term trends, holiday periods and school days when analysing the data.
Their research extends previous studies showing increases in adult and overall mental health presentations to EDs as temperatures rise. This is the first study to examine presentations among youth in NSW.
While the increase may sound small, it is cause for concern, experts say. Youth suicidality and suicide have been on the rise, and suicide is the leading cause of death for those aged 15 to 24.
Dr Dey said the linear increase in ED visits suggested a biological mechanism may be at play when young people get too hot, but stressed further investigation was needed.
“There was an increase on the first moderate hot day, which tells us it is more likely to be a biological effect, rather than a flow-on effect from factors like poor sleep.
“The heat itself looks to be doing something to increase people’s distress and that is supported by other literature. We know that calls to mental health crisis lines go up with temperature and there are overseas studies showing a link between heat exposure and suicidality presentations.”
A further breakdown of the data showed the effect was strongest in Western Sydney, inland rural and regional NSW, and weaker in Sydney’s inner suburbs and coastal regions, even at similar temperatures.
Senior author Dr Iain Perkes, a psychiatrist and senior lecturer with UNSW’s School of Clinical Medicine, said socio-economic disadvantage, which is associated with poorer quality housing, made it more challenging for people in areas like Western Sydney to cope with hot weather. More limited access to green spaces and waterways were also likely contributing factors.
“We’ll need to do more research on these possible mediating factors, but that shouldn’t stop us from getting on and making sensible changes to reduce exposure to higher temperatures,” Dr Perkes said.
Improving housing quality and access to cool environments, both at home and school, would help better protect youth. Targeted interventions for at-risk groups would also be key, as would a shift in public health measures and messaging, which typically focused on heatwaves and physical health.
“With temperatures on the rise it is critical that we do further work to better protect youth, and all people, from heat related health risks,” Dr Dey said.
Further resources to support the mental health of children and adolescents, and tips for being heat aware, can be found
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