Heatwave and Mental Health: One in five Canadians suffer from mental illness!


Heatwave and Mental Health: The period of extreme heat continues. For the third consecutive year, meteorologists have predicted that the heatwave will last for more than 10 days. Usually, these days are 4-8. Amidst all the difficulties, the number of people reaching the hospital with mental health problems increases in this season. Anyway, the last 10 years were the hottest on record. Therefore, from a health point of view, now is the time to take steps to increase your preparations for extreme heat.


Heat stress, heat exhaustion, and the potential for heat stroke are some of the dangers posed by extreme heat. However, physical health is not the only factor that is affected by extreme heat. Mental health can also be impaired. Many people can feel uncomfortable and uneasy during the summer months, as well as unable to sleep at night. But for people with mental illnesses, the danger of extreme heat is even more serious than natural reactions to everyday disturbances. 

Schizophrenia risk

Research by Peter Crank, a climatologist at Canada's University of Waterloo, and others during the 2021 Heat Dome in British Columbia says heat is aggravating existing mental illnesses. People with schizophrenia are more likely to be hospitalized and even die in hot conditions. The links between environment and health are increasingly being recognized by researchers as public health concerns as heat-related deaths make headlines alongside air and water quality issues. Research has shown that people from lower socioeconomic groups, racialized people, and homeless people are at greater risk of exposure to hot conditions, while the elderly are more vulnerable to hot conditions. 

Heat and Mental Illness

The relationship between mental illness and temperature has only recently been determined as medical records and understanding of mental illnesses have improved. As an urban climatologist, Peter Crank's research focuses on the effects of urbanization and heat on human health. "I explore a variety of unexpected effects of heat on people. In particular, I have studied populations with schizophrenia. Schizophrenia is a mental illness that disrupts the transmission of information to the brain. The part of the brain that is most affected also has our thermoregulatory functions. This is the part that tells us we are too hot and we start to sweat or we are too cold and we must shiver to stay warm. So people with schizophrenia are not able to react to extreme heat in the same way as the general population; their bodies do not tell them to take precautions. In addition, the medications used to manage schizophrenia also raise the core body temperature. This means that when taking the medication, people with schizophrenia are closer to the threshold for heat stress and stroke than the general population. In studying hospitalizations for schizophrenia in Florida between 2006 and 2014 (where summer night temperatures average 30°C) I found that minimum air temperature (low night temperatures) was significantly associated with the number of hospitalizations for schizophrenia. About three percent of hospitalizations for schizophrenia during that period could be attributed to low night temperatures. Risk is highest in both extreme cold (less than 3°C) and extreme hot conditions (greater than 30°C). Hospitalizations under these conditions cost the Phoenix health care system more than US$2 million (in 2024 US dollars).' 

One in five Canadians suffer from mental illness

According to Peter Crank, certainly, Canadians experience nighttime temperatures colder than 3 degrees Celsius, but they rarely experience minimum temperatures above 30 degrees Celsius at night. However, as a result of the 2021 Heat Dome, researchers found that schizophrenia is the chronic condition most associated with an increased risk of death during extreme heat. Extreme heat can have a devastating impact on people with mental illness, our health care system, and our communities. Schizophrenia is not the most common mental illness in Canada. However, it can serve as an example of how environmental issues can affect mental illness. One in five Canadians experience a mental illness each year. 

More than 250,000 Canadian youth experience severe depression and systemic inequities are exacerbated by inequities in the treatment and care of people who experience mental illness. While many different factors potentially contribute to mental illness, heat plays a pervasive role in a wide range of mental health problems. Actions we can take to reduce this burden on people with mental illnesses can also have benefits for the rest of society, such as reduced use of hospital emergency departments during heat waves. 

How to prevent deaths

If climate change is causing heat waves, what can be done to prevent hospitalizations and deaths that result from them? Some measures have wider benefits than improving mental illness outcomes during extreme heat. There is a better way: designing our cities to be greener. Greening cities has many already-known benefits; reducing urban heat, improving air quality, and in some cases increasing property values ​​(this has both positive and negative consequences). However, it also has some mental health benefits. 

Peter Crank contributed a review of urban greenery mitigation science and highlighted mental health benefits including a reduction in depression, irritability, and aggression. Urban green space has been shown to improve mood, and self-esteem and even help in faster recovery from illness.