During heat waves, hospital admissions for mental health issues surge. The past decade has been the hottest on record, and as we brace for another scorching summer, it’s essential to enhance our preparedness for extreme heat.
While heat stress, heat exhaustion, and heat stroke are well-known hazards of extreme heat, the impact on mental health is equally significant. Many people can relate to sleepless nights and increased irritation during hot summer months. However, for individuals with mental illnesses, extreme heat poses a far more severe risk.
Research from Phoenix, Arizona, and studies conducted during the 2021 heat dome in British Columbia reveal that extreme heat exacerbates existing mental illnesses, increasing the likelihood of hospitalization and even death, particularly among people with schizophrenia.
Heat and Mental Illness
The relationship between mental illness and temperature has only recently been quantified as medical records and our understanding of mental illnesses have improved. As an urban climatologist, my research focuses on how urbanization and heat impact human health. Specifically, I’ve studied the effects of heat on people with schizophrenia.
Schizophrenia disrupts the transmission of information to the brain, affecting the part responsible for thermoregulation. This means individuals with schizophrenia may not perceive heat correctly or take necessary precautions. Furthermore, medications for schizophrenia can raise core body temperature, making these individuals more susceptible to heat stress and stroke.
In Phoenix, where summer nighttime temperatures average 30°C, my study from 2006 to 2014 found that minimum air temperature significantly correlated with schizophrenia hospitalizations. Approximately three percent of all schizophrenia hospitalizations during this period were attributable to high nighttime temperatures. The risk was highest in both extremely cold (below 3°C) and extremely hot conditions (above 30°C). These hospitalizations cost the Phoenix healthcare system over $2 million (in 2024 USD).
The 2021 heat dome in British Columbia, which caused over 600 deaths, demonstrated that schizophrenia was the chronic condition most associated with the risk of death during extreme heat. This highlights the severe impact of extreme heat on those with mental illnesses and underscores the need for targeted interventions.
Coping with Climate Change
With climate change bringing hotter summers, it’s crucial to prevent heat-related hospitalizations and deaths. Measures that broadly improve mental health outcomes during extreme heat include ensuring access to air conditioning. Statistics Canada has emphasized the importance of air conditioning for vulnerable populations. As parts of Canada become increasingly hot, air conditioning is essential for maintaining safe indoor temperatures.
However, air conditioning relies on the electrical grid and contributes to greenhouse gas emissions. A more sustainable solution is to design greener cities. Urban greenery has well-documented benefits, including reducing the urban heat island effect, improving air quality, and potentially increasing property values.
Moreover, urban green spaces offer mental health benefits such as reduced depression, irritation, and aggression. Studies have shown that green spaces can improve mood, self-esteem, and even speed up recovery from illness.
As temperatures rise and we turn to air conditioning and cold drinks, it’s important to recognize the broader impacts of heat on our mental health. Extreme heat will continue to affect Canada, and by taking steps to create greener, more sustainable cities, we can mitigate its negative effects on our most vulnerable populations, including those living with mental illnesses.
