Sometimes you yawn when you're sleepy
and sometimes you yawn when you're just plain bored. We've all experienced a deep, wide-mouthed yawn at some time or another. But what you may not realize is that the frequency of your yawns change with the season. Believe it or not, you're more likely to yawn in the winter months than summer. Why? According to one study, the seasonal disparity indicates that yawning could be the body's attempt to regulate brain temperature.
Andrew Gallup from Princeton University's Department of Ecology and Evolutionary Biology and his co-author Omar Eldakar from the University of Arizona's Center for Insect Science, documented how frequently 160 study participants yawned in the summer and winter in Tucson, Arizona (with 80 people for each season). They found the participants were more likely to yawn in colder months than summer when the outside temperature was equal to or greater than body temperature. Gallup and Eldakur concluded that the warmer temperatures offered no relief for overheated brains. By contrast, the winter months provided heat exchange with the cooler air taken in during a yawn. The thermoregulatory theory of yawning.
It may sound complicated but Gallup explains the findings like this: “Enter the brain cooling, or thermoregulatory, hypothesis, which proposes that yawning is triggered by increases in brain temperature, and that the physiological consequences of a yawn act to promote brain cooling. I participated in a study [published in Frontiers in Evolutionary Neuroscience in September 2010] that confirmed this dynamic after we observed changes in the brain temperature of rats before and after the animals yawned. The cooling effect of yawning is thought to result from enhanced blood flow to the brain caused by stretching of the jaw, as well as countercurrent heat exchange with the ambient air that accompanies the deep inhalation.”
In simpler terms, you yawn because your brain is heating up and yawning cools it down. Why study yawning in the first place?
Sure, the study is interesting, but in the big scheme of things how does this information further science?
Gallup says, “This is the first report to show that yawning frequency varies from season to season. The applications of this research are intriguing, not only in terms of basic physiological knowledge, but also for better understanding diseases and conditions, such as multiple sclerosis
, that are accompanied by frequent yawning and thermoregulatory dysfunction. These results provide additional support for the view that excessive yawning may be used as a diagnostic tool for identifying instances of diminished thermoregulation.”
Based on Gallup's explanation, yawning frequency could possibly advance medical science as a tool for diagnosing certain conditions. Perhaps one day the question “do you yawn excessively?” will be part of the medical history questionnaire your doctor uses to pinpoint the onset of disease.