Another attempt to explain the mystery of why people yawn:
“A thermal window for yawning in humans: Yawning as a brain cooling mechanism,” Jorg J.M. Massen [pictured here], Kim Dusch, Omar Tonsi Eldakar, Andrew C. Gallup, Physiology & Behavior, epub 2014. (Thanks to @ThatNeilMartin for bringing this to our attention.) The authors, at the University of Vienna, Vienna, Austria, Nova Southeastern University, Ft. Lauderdale, USA and SUNY College at Oneonta, USA explain:
“The thermoregulatory theory of yawning posits that yawns function to cool the brain in part due to counter-current heat exchange with the deep inhalation of ambient air. Consequently, yawning should be constrained to an optimal thermal zone or range of temperature, i.e., a thermal window, in which we should expect a lower frequency at extreme temperatures. Previous research shows that yawn frequency diminishes as ambient temperatures rise and approach body temperature, but a lower bound to the thermal window has not been demonstrated. To test this, a total of 120 pedestrians were sampled for susceptibly to self-reported yawn contagion during distinct temperature ranges and seasons (winter: 1.4 °C, n = 60; summer: 19.4 °C, n = 60). As predicted, the proportion of pedestrians reporting yawning was significantly lower during winter than in summer.”
Here’s detail from the study:
