If your head is overheated, there’s a good chance you’ll yawn soon,according to a new study that found the primary purpose of yawning isto control brain temperature.
The finding solves several mysteries about yawning, such as why it’smost commonly done just before and after sleeping, why certain diseaseslead to excessive yawning, and why breathing through the nose andcooling off the forehead often stop yawning.
The key yawn instigator appears to be brain temperature.
“Brains are like computers,” Andrew Gallup, a researcher in theDepartment of Biology at Binghamton University who led the study, toldDiscovery News. “They operate most efficiently when cool, and physicaladaptations have evolved to allow maximum cooling of the brain.”
He and colleagues Michael Miller and Anne Clark analyzed yawning inparakeets as representative vertebrates because the birds haverelatively large brains, live wild in Australia, which is subject tofrequent temperature swings, and, most importantly, do not engage in contagious yawning, as humans and some other animals do.
Contagious yawning is thought to be an evolved mechanism for keepinggroups alert so they “remain vigilant against danger,” Gallup said.
