A thermal window for yawning in humans: yawning as a brain cooling mechanism.
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 (18.3% vs. 41.7%), with temperature being the only significant predictor of these differences across seasons. The underlying mechanism for yawning in humans, both spontaneous and contagious, appears to be involved in brain thermoregulation.
Department of Cognitive Biology, University of Vienna, Vienna, Austria. Electronic address: jorgmassen@gmail.com.
Jorg J M
JJ
Massen
Department of Education, University of Vienna, Vienna, Austria.
Kim
K
Dusch
Farquhar College of Arts and Sciences, Nova Southeastern University, Ft. Lauderdale, USA.
Omar Tonsi
OT
Eldakar
Psychology Department, SUNY College at Oneonta, USA. Electronic address: a.c.gallup@gmail.com.
Andrew C
AC
Gallup
D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D003625:Data Collection; D005260:Female; D006801:Humans; D008297:Male; D008959:Models, Neurological; D012621:Seasons; D012919:Social Behavior; D013696:Temperature; D015000:Yawning / Q000502:physiology*
Ambient temperature; Contagious yawning; Thermoregulation; Yawning