A study published in 1998 the journal Psychiatric Services found that patients in state psychiatric hospitals in New York City had twice the risk of dying during a heat wave compared with the general population of New York City.[5] The authors theorized that both the illnesses and the use of antipsychotic may have contributed to this correlation.
It's significant to note that suicide rates are higher during abnormally hot months. A study published in the Nature Climate Change journal showed an association between a rise of 1 degree C (about 1.8 degrees F) in average monthly temperatures and an increase of suicide rates by 0.7 percent in the United States and 2.1 percent in Mexico.[6] The researchers estimated that, without action to address it, climate change might account for as many as 9,000 to 40,000 additional suicides by 2050 in the United States and Mexico.
“That number just wipes out the contributions of every suicide prevention program and all the gun legislation efforts,” says Cooper about the prediction.

Why Does Extreme Heat Worsen Mental Health?
Researchers haven’t identified an exact reason why extreme heat is linked to worsening mental health symptoms, but according to Cooper, several complex factors probably play a role.

Here are five of these factors.

Heat May Hamper Brain Function
Extreme temperatures could spell trouble for how your brain operates in several ways. 

The hypothalamus, an area of the brain that helps regulate the body's internal temperature (and also helps with basic functioning, like hunger, thirst, mood, sex drive, blood pressure, and sleep), may not function normally when people with certain health conditions are exposed to extreme heat, Cooper says. "It's pretty clear that there is something biologically happening," she explains.

Research also shows extreme heat may hamper working memory and attention. In a paper published in 2018 in the journal PLoS college students who studied in rooms without air conditioning during a heat wave performed as much as 13.4 percent worse than their peers on a series of cognitive tests.[7]
Heat may also interfere with the brain chemical serotonin, which helps regulate mood and alleviate aggression, according to the World Economic Forum.[8]
Though more research is needed to better understand the brain’s response to extreme heat, Cooper says it’s clear that brain chemistry plays a role.

Certain Mental Health Conditions May Predispose You to Heat Issues
“There is some evidence that the mental illness itself may have some adverse impacts on thermoregulation in the body — that’s the body’s ability to stay cool,” says Cooper.

For instance, according to a review published in the journal Schizophrenia Research, people with schizophrenia have a harder time adjusting to hotter temperatures than people without this condition. In a more recent study, scientists found that exposure to heat was associated with an elevated risk of hospitalization among people with schizophrenia.[9]
Psychiatric Might Alter How Your Body Regulates Heat
The people with mental health conditions take to control their symptoms — such as antidepressants and antipsychotics — may affect how their bodies respond to heat, the APA states.[1]
Along with people taking antipsychotics, those who take anticholinergic drugs — which are sometimes prescribed for depression — and anti-anxiety drugs appear to have an increased risk of hospitalization for heat-related illnesses during a heat wave, per a study published the journal European Psychiatry.[10]
The authors noted that individuals who take psychiatric should talk with their healthcare providers about the risks and benefits of using their during periods of extreme heat.

Hotter Temps Make It Harder to Sleep
When a heat wave strikes, our sleep often suffers. Experts believe this lack of quality sleep could have a ripple effect on people with mental health conditions. It’s well established in research that insufficient sleep can make symptoms of mood disorders, such as anxiety and depression, worse.

“Disturbed sleep and daytime discomfort during extreme heat might be the biological mechanisms that contribute to increased rates of emergency department visits, so these may be important things for patients to monitor,” says Dr. Nori-Sarma.

Dehydration Risk Is Higher During Heat Waves
Anyone can experience dehydration during periods of extreme heat, Mayo Clinic states.[11] For people with mental health conditions, dehydration can impair cognitive function and the effectiveness of , which in turn may worsen their mental health symptoms, says Cooper.
How to Beat the Heat
It's important for everyone, but especially someone with a preexisting mental health condition, to be proactive about staying cool during extreme heat.

Cooper recommends that you talk with your care team, including general practitioners, psychologists, and psychiatrists, about the potential risks of extreme heat and come up with preventive strategies before heat strikes.

Here are some simple but effective ways to stay cool, per the Climate Psychiatry Alliance:[12]
Keep rooms cool. Lower the shades to reduce heat, and use a fan. Note that if the room temperature is above 90 or 95 degrees F, fans will no longer cool the air.
Take cool showers. Jump in a cool shower or place a cool cloth on your face, neck, or arms to help counteract hot temperatures.
Wear the right clothing. Loose cotton fabrics are best for staying cool. Also, consider donning protective gear like a hat and sunglasses when you’re outdoors in the hot sun.
Drink enough water. Be sure to drink water throughout the day — and try to avoid beverages that contain caffeine and alcohol, because they can be dehydrating. On an ordinary day, women should consume about 11.5 cups of water a day, and men should consume about 15.5 cups per day, per the National Academies of Sciences, Engineering, and (NASEM) — and if you’re planning to be out and about in hot temperatures, you should drink even more than that, NASEM experts advise.[13]
Find a cool place. Locate a cooling center in your community, or visit an air-conditioned mall, library, or bookstore to retreat from the heat. Avoiding extreme heat for just a few hours a day can make a difference, according to Cooper.[14]
Take your meds. Always take your as prescribed unless your healthcare provider tells you otherwise.
Make a plan to get help if you need it. Have a strategy in place in case you experience signs of heat exhaustion. For instance, before a heat wave, ask a friend or family member to check in on you a couple times a day once outdoor temperatures spike.
Heat-Related Illness: Signs to Watch For
Watch out for symptoms of heat exhaustion, which can happen when your body gets too hot. According to the Centers for Disease Control and Prevention (CDC), signs of heat exhaustion include intense sweating, a weak and rapid pulse, nausea or vomiting, and weakness or tiredness.[15] If you're showing signs of heat exhaustion, move to a shaded or air-conditioned place, drink water, cool yourself off with damp sheets or a fan, or take a cool shower to lower your body temperature, Mayo Clinic advises.[16]

Another serious condition to watch out for, called heatstroke, occurs when your internal body temperature reaches at least 104 degrees F, according to the American Academy of Family Physicians.[17] In addition to a high fever, the CDC states, the signs of heatstroke include skin that’s hot, dry, red, or damp, a fast, strong pulse, headache, dizziness, nausea, or fainting. If you have symptoms of heatstroke, you should seek emergency medical attention immediately. People around you should try to help cool you off, but don't drink any fluids while you wait for medical help, Mayo Clinic experts warn.
The Takeaway
Rising temperatures can affect anyone and lead to heatstroke, heat exhaustion, and cardiovascular and respiratory problems. Research suggests that extreme heat can negatively impact mental health, especially among people with psychiatric conditions.

To mitigate the effect that extreme heat can have on our physical and mental health, proactive steps, such as staying indoors, drinking enough water, and wearing the right clothing, should be taken.