Yawn Maybe it’s because your brain is on fire. According to a study led by Andrew Gallup, a researcher at Princeton University (USA), yawning is not just an indicator of fatigue or boredom. In fact, Gallup has shown that the frequency with which we yawn varies according to the season of the year, and that people yawn less when the heat outdoors is higher than body temperature, which would be justified ifyawning helps the brain regulate its temperature.
In experiments with 160 subjects, the scientists found thatwe are more likely to yawn in winter, compared to summer, when the ambient temperature is equal to or higher than body temperature. “About half of the people in the winter sessions yawned, compared with less than a quarter of the participants in the summer,” explains Gallup, who has concluded thathigh external temperatures do not provide any relief for overheated brain, while when it is colder, a yawn serves to bring in fresh air and lower the temperature of our head.
“Our study supports thethermoregulatory hypothesis of yawning, which proposes that we open our mouth when the temperature of the brain increases, and that the physiological consequence is that our neurons cool down “, explains Gallup, who has published his work in the journal Frontiers in Evolutionary Neuroscience. When yawning, stretching the jaw increases blood flow to the brain, and inhaling air colder than the body allows heat exchange with the environment. “It is a thermal window”, adds the researcher, who warns thatyawning when it’s very hot outside could backfire.
