The research shows why people yawn when tired

Dec 20, 2008 00:01 GMT  ·  By
A morning yawn may act like a cup of coffee in providing people with energy for the day
   A morning yawn may act like a cup of coffee in providing people with energy for the day

A new scientific study finally shed some light on one of the most mysterious human behaviors, namely the yawn. While most people know that yawning occurs when they are sleepy, they are not aware of the fact that this process also serves to a variety of other purposes, all tied to the optimum functioning parameters of the brain. This applies in the cases of most species that present such involuntary intakes of breath.

In order to conduct the new study, researchers at Binghamton University, led by Andrew Gallup from the Department of Biology, analyzed a species of birds, the parakeets, and the changes its brain underwent while yawning. “Brains are like computers. They operate most efficiently when cool and physical adaptations have evolved to allow maximum cooling of the brain.” Group yawning is believed to help animals living in packs “remain vigilant against danger,” Gallup says.

One of the main reasons why the team selected the parakeets for the study was the fact that these birds almost never engaged in group yawning, so they were deemed reliable test subjects. During the tests, they were subjected to three temperatures – one that increased constantly, one that was high, to begin with, and one for control.

Examinations proved that the brain sought to cool itself by triggering the yawning reflex when the outside temperature was lower than that inside the body. “For instance, yawning should not occur when ambient temperatures exceed body temperature, as taking a deep inhalation of warm air would be counterproductive,” Gallup adds. “In addition, yawning when it is extremely cold may be maladaptive, as this may send unusually cold air to the brain, which may produce a thermal shock.”

“It is interesting to note that instances of excessive yawning in humans may be indicative of brain cooling problems. Bouts of excessive yawning often precede the onset of seizures in epileptic patients, and predict the onset of headaches in people who suffer from migraines,” New York State University psychologist, Professor Gordon Gallup Jr., who has not contributed to the latest paper, explains.