Last year was the world’s hottest year in recorded history, with Canada warming twice as fast as the global average. It turns out that your brain plays a role in helping you cope with the next heat wave, but it needs some support in the face of rising temperatures.
The thermostat of your body
Deep inside your brain lies the hypothalamus. It keeps your core body temperature Goldilocks-approved: Not too warm and not too cold—just right!
“The hypothalamus regulates body temperature by receiving signals from thermoreceptors located throughout the body,” explains emergency medicine physician Arie Francis, MD. “It then adjusts body temperature through various mechanisms.”
For example, Francis says if your brain senses you’re too hot, the hypothalamus might tell your body to produce sweat which is then turned into water vapour. If your body is too cold, it messages your body which raises your core temperature through shivering.
Alas, there’s only so much your hypothalamus can do, especially when it’s overheated.
This is your brain on heat
Your brain works overtime to moderate your body temperature. At a certain point, that heat affects your brain, too. “When you’re exposed to high temperatures, your body starts prioritizing cooling itself down [and] blood flow is redirected from your brain,” warns Sean Ormond, MD.
With fewer nutrients and less oxygen reaching your brain, your mental health and cognition decline. Many people “experience confusion and disorientation,” says David Tang, MD, an emergency physician with a background in sports and exercise medicine.
Last year, multiple tourists went missing on well-marked hikes during Europe’s catastrophic heat wave. Some hypothesize that the heat caused these otherwise healthy individuals to get confused and make poor judgment calls.
If not treated immediately, extended heat exposure leads to dire results. “If you stay in the heat too long, your brain can start swelling,” adds Ormond. “That’s when things get more dangerous—heat exhaustion and heat stroke can kick in, [and] if you have conditions like migraines, chronic pain, or neurological issues, heat can make your symptoms worse.”
Thankfully, you can take active measures to support your hypothalamus and protect your brain (and body).
A hot trend
Ninety percent of Canada’s 10 hottest years took place just in the past two decades, and environmental modelling forecasts that this year will break heat records yet again. Reduced quality of life, illnesses, and deaths related to extreme heat cost Canada’s healthcare system billions of dollars a year.
Shield your brain from the heat
“The best time to prepare for extreme heat is before you even step outside,” advises family nurse practitioner Jung Baccam.
Check the forecast
Use a reputable source like Environment Canada to see the forecast and current heat index, but don’t just focus on the temperature.
“The risk of heat-related illness is highest during high humidity and prolonged sun exposure,” says Francis. On hot and humid days, he recommends avoiding the outdoors from 10 am to 4 pm when heat tends to peak.
Dress to impress (your brain)
“Wear loose, light-coloured clothing, a hat and sunglasses, and sunscreen,” says Baccam.
Mineral-based sunscreens may help you stay cool by deflecting sunlight. The sun’s ultraviolet rays also reduce your blood circulation—healthy circulation is key for regulating temperature—adding to sunscreen’s cooling benefits.
Embrace the siesta
There’s a reason many people in warm climates enjoy a midday siesta. “Take breaks in the shade or air conditioning whenever possible,” suggests Ormond. He also recommends regularly using cooling towels or misting sprays.
Help your body and brain recover
“After being in extreme heat, rehydrate,” says Ormond. On especially hot days, that may not be enough. “Take a cool (not freezing) shower to bring your body temperature down gradually,” he adds, “and rest in a cool, dark room; your brain needs time to recover.”
Try applying a cold cloth to pulse points. Your armpits and neck are great options—there are more surface-level blood vessels in these areas to help you cool down faster.
A cool outlook on a hot future
“Heat waves are becoming more common, and we all need to be more aware of how they impact our health,” says Ormond. He says that governments need to invest in infrastructure that keeps us cool (for example, green roofs and a focus on tree planting), but it’s also on us as individuals.
“We need to build habits that protect us,” he concludes. “Heat can be dangerous, but if you listen to your body and take the right precautions, you can stay safe—even on the hottest days.”
Hydrate against the heat
“One of the best tools to combat the impacts of extreme heat is hydration,” says Kevin Hoffman, DO. “When your brain struggles to operate optimally, dehydration amplifies that effect.”
Warning signs of dehydration
“Symptoms of heat-related brain dysfunction include dizziness, confusion, headaches, nausea, and difficulty concentrating,” says Arie Francis, MD. If you notice these symptoms, rehydrate and seek shade or air conditioning. More severe symptoms include slurred speech and hallucinations. In these cases, seek medical attention.
Hydrate throughout the day
“Keep sipping water—don’t wait until you’re thirsty,” advises Sean Ormond, MD. That includes getting hydrated before you head into the heat. Most adults need 9 to 13 cups (2.25 to 3.25 L) of fluids a day for healthy hydration.
Supercharge with electrolytes
“Electrolytes matter because sweat drains your body of sodium, potassium, and magnesium,” says Ormond. “Replace lost electrolytes with sports drinks, coconut water, or electrolyte tablets.”
Eat your drink
“Equally important to hydration are lifestyle habits,” says Hoffman. “Eat water-rich foods like cucumbers and watermelon, and skip alcohol or caffeine—they dehydrate the body.”
This article was originally published in the June 2025 issue of alive magazine.
Joshua Duvauchelle is a regular alive contributor and certified personal trainer who lives in Victoria, BC.
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