It’s easy to be offended when a colleague yawns while you’re talking. But that yawn may not mean what you think.
A growing number of researchers believe the purpose of this little-understood behavior is to cool the brain, says a research review published earlier this year in Frontiers in Neuroscience.
Changes in climate affect how often people yawn. Researchers in an earlier study asked two groups of pedestrians in Tucson, Ariz., one in early summer and one in the winter. People were asked to look at pictures of people yawning and talk about their own yawning behavior.
The participants were nearly twice as likely to yawn when they were surveyed during the winter, when they could inhale cool air to reduce the temperature of the brain, says the study, published in 2011 in Frontiers in Evolutionary Neuroscience. Participants yawned less when surveyed in the early summer, when temperatures outdoors were about the same as the human body.