Cool tips for when things get hot

The heat slows us, physically and mentally. Here’s how to avoid the worst of it

Staying cool and avoiding the heat is important for you health in summer Picture: iStock 

Hot weather can leave us feeling tired and take a toll on our mental performance, making us sluggish and unfocused.

We spoke to cognitive rehabilitation therapist Natalie Mackenzie, also known as The Cognitive Strategist, who explained some of the reasons behind this heat-related brain fog.

Why are cognitive functions, such as memory and concentration, often impacted by heat?

During a heatwave, the brain’s hypothalamus redirects energy and blood flow toward the skin to cool the body, says Mackenzie.

“Our hypothalamus, which is the brain’s thermostat, constantly monitors body temperature and makes sure that when our temperature goes up, our body cools down through sweating,” says Mackenzie.

“Our heart rate also increases during the heat, which diverts a lot of energy and blood flow away from the brain, which can affect cognitive function. Things like attention and concentration, which are at the bottom of the cognitive pyramid, tend to be affected first.”

This can have knock-on effects on other cognitive functions, like our memory.

“This [response] creates problems with filtering, distraction, and focus, which then impacts working memory, which is in the next layer of the pyramid,” says Mackenzie.

“This is because if people can’t focus and attend, then they can’t keep things in their working memory, can’t hold information, and can’t manipulate it to then put it into longer-term memory.”

We can also experience problems with decision-making and executive function — which are higher-level cognitive functions — in the heat.

“People can’t weigh up information as much, processing speed slows, and people often experience a cascading effect that goes down the different cognitive domains,” says Mackenzie.

Can the heat also impact our mood?

“Some people find that because their decision-making is impaired, or because their body feels under stress, this can impact their emotional responses,” says Mackenzie. “In the heat, our blood flow and body are focused on our survival instincts of cooling down, which can make us go into a more emotional state.

“People often feel more snappy, and potentially more reactive and impulsive, in the heat, because they are not utilising those executive functions as well as they usually do.”

What role can sleep play in this?

Heat can affect our sleep, which can impact our mood and cognitive function the following day.

“We want to see a little dip in body temperature to get into that deep sleep state that we need for restorative sleep, but when it’s hot, this can be an issue,” says Mackenzie.

“Less time in this deep-sleep state impacts our sleep architecture, which then impacts memory consolidation and can impact the glymphatic waste-clearance process [which keeps your brain tidy by clearing out waste while you sleep, according to the Cleveland Clinic]. Then, the following day, you get the compound effects of the cognitive impact of poor sleep.”

Does dehydration play a part in this?

“Even a small fluctuation in hydration, just tipping into slight dehydration, significantly impacts cognitive function, such as decision-making and focus,” says Mackenzie.

Here are Mackenzie’s top tips about how to prevent and manage these effects:

Focus on fluids: “It’s important not to forget to stay hydrated,” says Mackenzie. “We also sweat more during a heatwave, so it’s not just about keeping up your normal water intake, as you need to replace the water you lose through sweating.”

Adjust your schedule: “Consider changing your schedule, if you can. For example, start work earlier in the day, when it’s a bit cooler,” says Mackenzie.

Change your environment: “Try to stay away from hot offices, if possible, and stick to cooler environments,” says Mackenzie.

Reorganise your day: “Consider changing how you plan your day around decision making,” says Mackenzie. “For example, I would recommend doing the more cognitively demanding tasks in the morning or the early evening, when it’s cooler.

“Try to avoid or reduce making any important decisions during peak heat times.”

Have a slightly cooler shower: “Lower your body temperature with a slightly cooler shower rather than a freezing cold shower,” says Mackenzie. “Cooling down your wrists and your neck can help reduce that hypothalamic response.”

Create a cool sleeping environment: “Try to keep yourself cool at night,” says Mackenzie. “Things like fans, no sheets, and light cotton can all help protect that sleep and help you get more deep sleep.”