Around the world, several devastating heatwaves are ongoing with forest fires and extreme temperatures threatening human life and well-being. The detrimental effects of extreme heat on physical health and ecosystems have received significant attention. But heatwaves can also have a profound impact on mental health, and this has not been widely recognised so far. In this blog post, we dive into the science behind heat and mental health. We discuss the underlying mechanisms and the urgent need for proactive measures to protect the psychological well-being of individuals during extreme heat events.

Whilst the connection between heat and mental health might not be immediately apparent, research has begun to uncover the intricate relationship between the two. The foremost impact of heatwaves on health stems from the physiological responses of the human body to extreme heat. When exposed to high temperatures, our bodies strive to regulate internal temperature through perspiration and dilation of blood vessels. One study showed that rats exposure to extreme heat (heat maintained at 43 °C and 60 ± 10 % humidity for 15 min once a day) was enough to lead to changes in the hippocampus, a small structure deep in the brain linked to memory and many other cognitive functions. These changes are easily measurable in animal research. But how does heat alter human mental health?

Burke and colleagues tested the association between extreme heat and suicide in the US and Mexico. The authors showed that monthly temperature was associated with monthly suicide rates in both countries. This was different from the relationship between heat and ‘all-cause mortality’: death from all causes, which typically increases at both extreme hot and cold temperatures. Worryingly, the authors also looked for whether various adaptation measures, such as air conditioning could lessen the health-related impacts of climate over time. However, there was no statistically significant decline in the association between temperature and suicide, suggesting increasing air conditioning was not making a difference.

Read the full article about extreme heat and mental health by Patricia Lockwood and Jo Cutler at Psychology Today .