Are We Dumber in the Summer?

This summer, I found myself struggling with more tip-of-the-tongue words than usual. The ever-elusive names, of course, but also common words. Words like…Oh, shoot. It’s happening again. What do you call that thing you put on the dog? Not a collar, but the one with four straps?

(Two minutes later): Harness!

So, I thought, “Am I dumber in the summer?”

The answer seems to be, “Yes.” I am dumber in the summer, and so are you. But why? And can we do anything to counter it?

Was Mel Tormé Right? Is it Just Tooooo Darn Hot?

Maybe it’s the sweltering temperatures that affect our thinking?

A group of scientists in the UK brought volunteers into the lab to measure their mental agility in two thermal conditions: room temperature (70 °F) and an oppressively hot environment (103 °F). By the way, when I read this study, I wondered, “Why were all of the participants male?” Then I noticed how the researchers measured body core temperatures in the volunteers. You guessed it. A rectal probe. I might be wrong, but I’m guessing female volunteers paused on that line in the consent form and thought, “Uh. No.” 

What were the results? When in a hot room, people did worse on a computer task that measures inhibition—that’s our ability to not pay attention to something.

You might ask if inhibition is even important. To that I would say, “Yessiree Bob.” Imagine if you had to struggle to ignore things — the distracting signs you drive by on the highway or your irritating spouse. We need inhibitory control to get through the day (without murdering our loved ones).

What other tasks suffer in sweaty weather? Heat stress causes impairment on both simple and complex cognitive tasks.

However, it’s much worse when doing something more demanding. These activities include things like doing mental arithmetic, planning how to solve a problem, and driving. Ah. Driving. That clocks. To me, summer drivers do seem more clueless. And steamy Florida is legendary for drivers making suboptimal decisions. Here’s just one from the news. A woman in the Florida Keys rear-ended a car because she was trying to shave her “bikini area” while driving. Luckily, there were only minor injuries.

What are the Key Mechanisms for Heat Effects?

So we’ve established we are dumber in the summer. But why? A number of biological mechanisms are in play. For instance, mental slowing results from dehydration and from heat-induced changes in blood flow in the brain.

Subjective feelings also seem to matter. For instance, Kimberly Meidenbaur, a scientist near me at WSU, has investigated whether thermal discomfort is associated with performing poorly on cognitive tasks.

Participants wore smartwatches for two weeks so that researchers could randomly send them a cognitive test and ask them survey questions. The cognitive task was a “1-back” task. That is, participants had to remember what happened 1 trial back, then say whether each shape they saw was the same or different than the shape they just saw. As simple as this task might seem, it can measure several high-level cognitive functions, like holding information, comparing it, and inhibiting old information.

The results showed that subjective temperature discomfort was linked to worse scores. Interestingly, the research team found that the harm from discomfort could be either from being too hot or too cold.

This explanation—a psychological drain when temperatures get uncomfortable—rings true for me personally. Maybe it’s because I was raised in the temperate climate in Seattle, but both my mood and thinking suffer if I get the hot crankies. And by “hot” I mean anything over 73 °F.

Smoke Gets in Your Eyes (and Maybe Your Brain?)

Right now, I live in the Pacific Northwest of the US. Here, as in many places, our summers are getting more and more smoky from wildfires.

I personally seem to have more headaches on really smoky days, and I wondered if these pollutants were affecting my brain and thinking.

Unfortunately, they probably are. A recent review showed that our brains are impacted by extreme heat, wildfire smoke, and the combo of the two. Specifically, these conditions are associated with inflammation in the brain and disruptions in neuronal signaling (the basis of all thinking).

You might remember from your science classes that correlation does not necessarily imply causation. True. But studies with rats randomly assigned to smoke exposure do. From this research, we know that it’s the smoke particulates causing changes in the brain. And these are not happy changes. They’re linked to diseases such as stroke and Alzheimer’s disease.

“But maybe these alterations in our brains don’t translate to everyday cognitive glitches,” you might be saying. Well, bad news there, too. Researchers followed a large group of people for a year, tracking their scores on a test of selective attention and how they aligned with smoke levels. The two measures matched up. As concentrations of wildfire smoke and particulates went up, focused attention scores went down.

Maybe we’d better step up those Smokey Bear ads again.

Now that I’ve Freaked You Out, Is There Anything to Do to Counter the Effects?

1. Stay cool. You know the usual advice. For instance, use A/C or fans, limit outdoor time, and avoid physical activity during the blazing hot hours (isn’t it great to hear advice to exercise less?)

2. Stay hydrated. Here’s an easy way to check. Your goal should be light-to-clear colored pee.

3. Minimize exposure to wildfire smoke, and basically any other airborne pollutants. Tips for this include using A/C and avoiding any heavy breathing activities when the air quality is bad (for example, exercising, and, well, use your imagination).

4. Listen to music with a “groove.” Sounds crazy, but hear me out. One study found that listening to a groove rhythm—that is, a beat that makes you want to move to the music— leads to better performance on a difficult cognitive task. So, when your brain gets sluggish in the heat, heed the sage advice of Peaches & Herb and “shake your groove thing, shake your groove thing, yeah, yeah.”