Why we yawn

Ever wonder why you yawn? A recent study published in the journal Physiology and Behavior supports a theory that the reason why we yawn is to cool our brains down. Turns out that yawns are preceded by warmer-than-normal brain temperature, and are followed immediately by a cooler brain. Check this out:

I had a look at the study. It was a fun experiment. The experimenters approached people in public places in the city of Vienna and asked them to participate in a survey about contagious yawning (the phenomenon wherein we yawn when we see, hear about, or think about someone else yawning), look at a series of pictures of people yawning, and then fill out a brief survey reporting how often they had yawned, or felt the urge to yawn, during the process. The experiment was conducted once during the winter, and again during the summer, and the researchers were collecting temperature and humidity data during each person’s participation. Sure enough, the warmer it was when someone took the survey, the more likely it was that they yawned. Interestingly, that was only true up to a point, though. A previous study conducted in Tuscon, AZ when the temperature was over 37°C (i.e., body temperature), found that yawning decreased at that temperature. This also aligns with the theory, because filling the lungs with body-temperature air wouldn’t have any cooling effect.

As for the phenomenon of contagious yawning, researchers think it’s a way of promoting the wide distribution of peak levels of vigilance within a social group, because when the brains of all group members are working optimally, they’ll be more likely to spot predators, potential food sources, etc.

Because, of course, cooler heads always prevail.

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