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Key points
- Rising temperatures can elevate cortisol levels and trigger stress responses.
- A recent study found that emergency room visits for mental health conditions rise on extremely hot days.
- Spikes in temperature can affect our cognitive function and productivity at work, school, and home.
As rising temperatures continue to break records this summer, it is important to remember that extreme heat affects not just our physical health but also our mental health.
Elevated cortisol levels, induced by rising temperatures, can trigger stress responses, making individuals feel moody and agitated. The parasympathetic nervous system, responsible for promoting calmness and relaxation, becomes less active at higher temperatures, leaving us vulnerable to stress.
Commonly experienced side effects of heat on mental health include listlessness, changes in sleep patterns such as insomnia, heightened irritability, anger, anxiety, depression, and stress. While these psychological reactions might seem fleeting, they can have serious consequences. A 2022 study published in JAMA Psychiatry of over 2 million people found that hospital ER visits for mental health conditions rise during extremely hot days. Visits for substance abuse, anxiety, mood disorders, and schizophrenia all increased over a nine-year period when temperatures were elevated.
Spikes in temperature can also impair sleep and disrupt brain neurotransmitter function, directly affecting our cognitive function and productivity at work, school, and home. A 2018 study evaluated the differential impact of air conditioning on cognitive function in young adults residing in college dormitories during a heatwave. Some students enjoyed the comfort of central air conditioning, keeping their dorms at a pleasant 71°F. Meanwhile, others occupied rooms without air conditioning, subjecting them to temperatures around 80°F.
Across two weeks, the students participated in a series of tests on their phones each morning. Those who endured the warmer dorm conditions consistently displayed lower performance levels in the tests. The assessments included a basic math test involving simple addition and subtraction and the Stroop test. The Stroop test involves a mixture of colors and words designed to assess cognitive processing.
Another study demonstrated that productivity in the workplace is highest when the air temperature is about 72 degrees, and productivity starts to drop off in the mid-70s. All of the evidence from these studies point to a reduced ability to think clearly, quickly, and efficiently when the body is overheated.
While it may seem obvious, staying well hydrated can help lessen the impact of heat on mental health. Dehydration is common during extreme temperatures and can exacerbate cognitive impairments and mood disturbances. Many people underestimate how much fluid they need to replace when they're sweating a lot or spending time outdoors. Certain medications may also contribute to or increase dehydration.
It is critical to understand that climate change impacts not only the environment but also our physical and mental health. Recent studies in Lancet and Nature Climate Change found that an increase in temperature of even 1 degree Celsius can worsen depression, anxiety, and suicide rates. Conversations about improving our population's health cannot be siloed from discussions about climate change mitigation.
