Impact of Heat Waves on Mental Health

Recognizing the Association

If you find that the blistering, unrelenting heat is making you anxious and irritable, even depressed, it’s not all in your head. Soaring temperatures can damage not just the body but also the mind. As heat waves become more intense, more frequent and longer, it has become increasingly important to address the impact on mental health, scientists say.

Association with Suicides and Violent Crime

“It’s really only been over the past five years that there’s been a real recognition of the impact,” said Dr. Joshua Wortzel, chair of the American Psychiatric Association’s committee on climate change and mental health, which was set up just two years ago. “Our understanding of the basic biology of why this association exists is still in its infancy,” he added.

Research has shown that high temperatures are strongly associated with an increase in suicides and a rise in violent crime and aggression. Heat has also been linked to an increase in emergency room visits, hospitalizations for mental disorders, and deaths – particularly among individuals with schizophrenia, dementia, psychosis, and substance use.

Increased Risk of Death and Violence

For every 1 degree Celsius (or 1.8 degrees Fahrenheit) increase in temperature, scientists have estimated that there is a nearly 5 percent increase in the risk of death among patients with psychosis, dementia, or substance use. Additionally, a 0.7 percent increase in suicides and a 4 percent to 6 percent increase in interpersonal violence, including homicides, have been reported.

Exacerbation of Mental Illnesses

Heat not only fuels feelings like irritability and anger but also seems to worsen mental illnesses such as anxiety, schizophrenia, and depression. Vulnerable populations include older adults, adolescents, people with pre-existing mental illnesses, and those who do not have housing or are of lower socio-economic status.

A landmark study conducted last year analyzed data on over two million people with private insurance and found that emergency department visits for mental illnesses were significantly higher during the hottest days of summer compared to the coolest days of the season. The increase was most prominent in northern parts of the United States. Various mental health conditions, including mood and anxiety disorders, stress disorders, schizophrenia, substance use disorders, and self-harm, exhibited this trend.

Biological Explanations

Scientists have proposed several biological explanations for the connection between soaring temperatures and mental health disorders. Disrupted sleep due to warmer temperatures may be a simple origin for some mental illnesses. On warmer nights, people fall asleep later, wake up earlier, and experience poorer sleep quality. Prolonged periods of sleeping in overly warm rooms can exacerbate chronic conditions, negatively affect psychiatric disorders, increase suicide risk, impact memory, mood, and cognitive function.

Serotonin, a neurotransmitter linked to mood, anxiety, and depression, also regulates the body’s ability to sense temperature. Increased sunlight and heat can raise serotonin levels, leading to mood swings, aggression, and irritability. Certain widely used drugs, including antibiotics, beta blockers, some antidepressants, and antihistamines, can affect the body’s ability to sense and regulate body temperature as well.

Medications prescribed for schizophrenia, depression, and bipolar disorder, including widely used lithium, impair the body’s ability to sweat and cool itself. Extreme heat and sweating can lead to toxic levels of lithium in the body, resulting in serious physical and mental problems and even death.

Indirect Routes and Other Impacts

High temperatures can indirectly impact mental health through various routes. Crops absorbing fewer micronutrients due to hot weather can lead to nutrient deficiencies and subsequent psychiatric consequences. Rising temperatures expand the reach of disease vectors carrying pathogens that may cause psychiatric and neurological symptoms. Heat also increases allergens and pollutants, worsening air quality and triggering anxiety and depression.

The Mental Health Burden

Heat is only one aspect of climate change, and its immediate effect on mental health can be difficult to separate from emotions regarding the larger existential threat. The Intergovernmental Panel on Climate Change warns that rising temperatures will lead to deep anxiety, grief, and stress, particularly affecting children, adolescents, older adults, and those with chronic health problems.

Climate Distress and Coping Strategies

Scientists have coined the term “climate distress” to describe the multitude of emotions triggered by environmental changes. Cognitive behavioral therapy and medications, commonly used to cope with difficult emotions, may fall short when it comes to the climate crisis, as the threat is real. However, connecting with others and taking action at various levels can help alleviate climate distress.

Local governments can assist by planning for long stretches of hot days, providing information about cooling rooms for people without air-conditioning at home. Awareness and precautions regarding the interaction between certain medications and sunlight should also be increased. Ultimately, addressing mental health impacts in the face of climate change is crucial for the well-being of individuals and communities.