First we were told yawning meant we were tired. Then it was claimed yawning was the body's mechanism to keep us awake. Now a new study says yawning cools the brain.
The research, led by psychologist Andrew Gallup of SUNY College at Oneonta, claims yawns are the body's way of keeping temperature on an even keel and in "optimal homeostasis."
"Sleep cycles, cortical arousal and stress are all associated with fluctuations in brain temperature, Yawning subsequently functions to keep the brain temperature balanced and in optimal homeostasis," states a release on the study.
Previous research had revealed there is no association between yawning increasing oxygen supply, which would then likely feed a person's energy level.
In conducting the study the researchers measured "contagious" yawning frequencies of people in Austria during winter and summer months and compared the results to a similar study done in Arizona. People in both studies were asked to view a series of images of people yawning.
"Results showed that in Vienna people yawned more in summer than in winter, whereas in Arizona people yawned more in winter than in summer," stated the release. It seems it wasn't a matter of the season or daylight hours, but more an optimal thermal zone or ambient temperature that ignited yawning. Yawning dropped in high temps in Arizona and in very cold temps in Austria.
Lead author Jorg Massen explains where yawning functions to cool the brain, yawning is not functional when ambient temperatures are as hot as the body, and may not be necessary or may even have harmful consequences when it is freezing outside.
"While most research on contagious yawning emphasizes the influence of interpersonal and emotional-cognitive variables on its expression, this report adds to accumulating research suggesting that the underlying mechanism for yawning, both spontaneous and contagious forms, is involved in regulating brain temperature," states the release.
The study was published in "Physiology & Behavior" on April 12.