What Can We Do to Protect Our Brains From Heat?

As of June 24, 2024, the U.S. is seven days into a "heat dome," with extreme temperatures hammering much of the country. Things are only getting worse for some regions, including much of the Eastern U.S. and southwestern states like California and Nevada. While this heat wave is receiving valuable attention, making headlines and leading to the sharing of important health and safety precautions, heat waves are going to continue to be less newsworthy and more common in the face of our warming planet.

The physical health risks of heat exposure are well-known—dehydration, heat exhaustion, heat stroke, and the worsening of existing physical and mental health conditions, to highlight a few. Increasingly, researchers are highlighting the psychological and neurological effects of heat exposure. Our ability to think clearly worsens, our mood plummets, and we feel grumpy, tired, and even more impulsive and aggressive.

In part, this is because when we are experiencing hot weather, our bodies must devote valuable energy to cooling themselves down, a process called thermoregulation. This disrupts our brain’s typical functioning, making it harder to carry on with our daily activities and tasks that require a clear head.

So, with hotter weather and extreme heat becoming the new normal, and an increasing awareness of the psychological effects of heat, what can we do to protect our brains?

Staying Cool with Wearable Devices

One promising option comes from a recent study published in Building and Environment by researchers at the Worcester Polytechnic Institute. In this study, they tested the efficacy of personal cooling devices to mitigate feelings of temperature discomfort, negative emotions, and cognition.

They did so by bringing 60 undergraduate participants into an uncomfortably hot room, set at 37.5 degrees C (about 89 degrees F). Half of the participants completed ratings of their emotions and performed different cognitive tasks in those conditions while the other half did the same procedure, but had a personal cooling device placed on their upper back. They also measured skin temperature, perceptions of temperature comfort, and ratings of how hot they were.

They found that this cooling device did indeed reduce negative emotional states, particularly feelings of hostility and being afraid and upset. However, it didn’t impact cognitive performance on the types of tasks that heat typically affects—ones that require a lot of attention and working memory.

The lack of effect here might be due to the relatively modest heat exposure, and the fact that they didn’t see an overall effect of the device on full-body thermal comfort. A study in the Journal of Environmental Psychology in 2012 showed that when heat stress isn’t so extreme that it changes our core body temperature, thermal discomfort likely drives the impairments in cognition (Gaoua et al. 2012). Additionally, since this study with personal cooling devices didn’t have a neutral (room temperature) condition, it’s hard to say whether this hot room had an impact on performance more generally.

Nonetheless, the effects on emotional states are very promising, and it’s possible that in more extreme cases, the effects on cognition or comfort might be more pronounced. Indeed, some research has shown that head and neck cooling can help our brains function better in extremely hot temperatures (Xue et al., 2018)

Cooling Our Homes and Neighborhoods

For those living in homes with air conditioning and the financial means to pay for the energy bill, the solution for cooling down indoors is pretty straightforward. However, heat waves and increasing temperatures are hitting places that have historically not needed AC, leaving these areas more vulnerable to heat’s effects. The Pacific Northwest in the U.S. is one such area, with a historically mild climate that is increasingly experiencing the harmful effects of a warming planet.

However, access to AC is not just a regional issue, but one tightly linked to income and socio-economic status. Lower-income, racial minority neighborhoods in U.S. cities are more likely to be affected by the urban heat island (UHI) effect—the phenomenon where concrete, roads, and buildings amplify the effects of heat and sun.

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So how do we protect those without AC, without the means to pay for it, and exposed to even hotter temperatures due to the UHI effect? It’s not a straightforward problem, but there are a few things that can help.

One solution is to cool down areas naturally—that is, planting trees, gardens, "green roofs," and other types of greenspace infrastructure to bring the ambient temperature down. In contrast to concrete, tree canopy and other plants can remove heat from the environment, counteracting the urban heat island effect.

Exposure to natural spaces also provides profound psychological benefits in their own right (Berman et al., 2021). Indeed, a 2024 study in the journal Urban Climate suggested that thermal comfort may be a crucial part of nature’s restorative benefits in hot climates!

Unfortunately, infrastructure changes of this type are slow, and heat waves will still happen. Accessible and available cooling centers and air-conditioned public spaces (libraries, movie theaters) are essential for those who do not have adequate cooling in their home when extreme weather events hit.

Ultimately, dealing with heat is a complex problem and there’s no silver bullet or one-size-fits-all solution. While our climate crisis and the presence of compounding vulnerabilities are indeed cause for anxiety or pessimism, there is also hope.

Scientists are working hard to develop a better understanding of how heat affects our brains and gather evidence about what works and what doesn’t when it comes to protecting ourselves. And hopefully, we will be more prepared for the heat waves to come.