Scientists Begin to Understand Effect of Heat on Mental Health

Sound sleep is a crucial casualty, worsening certain conditions
By Bob Cronin,  Newser Staff
Posted Aug 10, 2023 6:25 PM CDT
Research Begins to Connect Heat to Physical, Mental Health
People cross a street in scorching heat at Ginza district in Tokyo last Friday.   (AP Photo/Shuji Kajiyama)

There's plenty of reason to think hot weather takes a psychological toll as well as a physical one. Researchers have found suicides increase when it's hot, as does violent crime, trips to the emergency room, hospitalizations for mental problems, and deaths overall, the New York Times reports. But the reasons aren't always clear, and one expert said the effects have only been widely acknowledged for five years or so. As prolonged heat waves become more common, research into the links becomes more important. "Our understanding of the basic biology of why this association exists is still in its infancy," said Dr. Joshua Wortzel, who chairs the American Psychiatric Association's committee on the subject.

The risk isn't evenly distributed. People who suffer from schizophrenia, dementia, psychosis, or substance use face increased danger—often a 5% higher risk of death for every 1.8 degrees Fahrenheit rise in temperature, one study estimated. Those who take drugs to deal with mental issues have to be especially careful when temperatures are high, said Dr. Ken Duckworth, chief medical officer at National Alliance on Mental Illness. "Some antipsychotic medications reduce the ability to control temperature," he said, per CNET. Being in air conditioning mitigates the risk, but patients on certain antipsychotic medications who are in the heat can find their body aligning with outdoor ambient temperatures, Duckworth said.

Anyone can become more irritable during hot spells. One reason for the greater strain on bodies is sleep disruptions. A good sleep is more likely when the room is no warmer than 68 degrees, per the Times. Also, people fall asleep later and wake up earlier during warm spells. Older people are affected more—one study found they lost twice as much sleep as young people. If that goes on for weeks, physical conditions such as heart disease and diabetes are exacerbated, as are cognitive function and psychiatric issues, research suggests.

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A psychiatrist in Houston detailed the basic connections. Dr. Asim Shah found that nearly every patient's pulse or heart rate on a recent summer afternoon was higher than it was three months before. "That increase in your heart rate can increase your anxiety," Shah said. "So heat causes a lot of physical changes, which leads to a lot of emotional and mental changes." It's not just the heat today but the climate's prognosis that upsets people. "It is unfortunately true that this may be the coolest summer for the rest of our lives," said the head of Stanford University's program on climate change and mental health, "which is unsettling to reckon with." (More extreme heat stories.)

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