Temperature-Dependent Variation in Self-Reported Contagious Yawning
Adaptive Human Behavior and Physiology
Yawning, Brain temperature, Ambient temperature, Thermoregulation, Contagious yawning, Climate variation
The thermoregulatory theory posits that yawns function to cool the brain in part due to counter-current heat exchange with the deep inhalation of ambient air. In support of this theory, previous cross-cultural research on humans has shown that self-reported contagious yawning frequency varies between seasons with distinct ambient temperature ranges. However, it remains possible that differences in yawning across seasons are a result of physiological circadian changes across the year rather than variation in ambient temperature. In an attempt to address this question, here we discuss the results of a study investigating the variation in the frequency of self-reported contagious yawning within a restricted range of a single season in one geographic location. A total of 142 pedestrians were recruited outdoors during an 18-day period over the summer in an equatorial monsoon climate in southern Florida, USA. Consistent with the thermoregulatory theory of yawning, results showed that self-reported contagious yawning frequency varied predictably across temperature gradients. This was true after statistically controlling for relative humidity, time of day, time spent outside, testing day, age of participant, and amount of sleep the night before. These findings provide further evidence suggesting a brain cooling function to yawning.
Eldakar, Omar T.; Melissa Dauzonne; Yana Prilutzkaya; Daniel Garcia; Carolyn Thadal; and Andrew C. Gallup. 2015. "Temperature-Dependent Variation in Self-Reported Contagious Yawning." Adaptive Human Behavior and Physiology 1, (4): 460-466. doi:10.1007/s40750-015-0024-6.