A University of Sydney study analysing 720,000 hospital admissions in New South Wales found that extreme high temperatures double the risk of young people being admitted for mental health conditions. The research, published in the Journal of the American Academy of Child and Adolescent Psychiatry, examined admissions of individuals aged up to 24 between 2001 and 2022.
Key Findings on Temperature and Mental Health
When daily average temperatures were in the highest 1% for that day, the risk of hospital admission doubled during warmer months (October to March) and tripled during cooler months. Lead author Dr Wen-Qiang He stated: “We found that as temperatures increase, we see admissions for these younger populations increase significantly. The risk doubles in the warm season and triples in the cold season. That’s important for us to know and if we can let the community know what’s happening, then we can prepare and help our children and young people.”
The study included serious hospital admissions for conditions such as schizophrenia, depression, substance misuse, eating disorders, and self-harm. Researchers noted that as extreme temperatures become more frequent due to global heating, heat-related hospital admissions could increase by 6% to 7.7% by the end of the century.
Possible Mechanisms and Implications
While the study did not determine causation, authors suggested several possible explanations. In warmer months, higher temperatures may directly affect brain function, impacting mental health. Unexpected temperature changes, common in winter, could alter stress responses, sleep, and mood. Co-author Dr Cybele Dey, an adolescent psychiatrist in Sydney, said: “These are not mild presentations. There has to be a lot going wrong for a person to be admitted. Climate change is already impacting children and young people’s mental health in multiple ways.”
Previous research has linked hotter-than-average days to increased hospital presentations for suicidal thoughts and behaviours in NSW youth. The National Climate Risk Assessment also warned that extreme heat is associated with higher rates of suicide and mental health-related admissions.
Expert Commentary on Practical Applications
Dr Hasini Gunasiri, a research fellow at Orygen, noted that during extreme heat, young people may use alcohol or substances to cope with discomfort, sleep disruption, or emotional distress. Heat can increase impulsivity and risk-taking behaviours. She said: “Sleep disruption may be especially relevant here. Poor sleep is a well-established risk factor for suicidal ideation and self-harm in young people. Current heat-health policies tend to focus on physical health outcomes such as heatstroke, dehydration and cardiovascular illness, particularly among older adults. These findings suggest that mental health should also be considered when planning for extreme temperatures, especially for children and young people.”
Gunasiri recommended integrating mental health messaging into heat warnings to raise awareness among clinicians and families about the potential mental health impacts of heat.
