Washington: Yawning, popularly considered a mark of boredom or fatigue, could serve as a method for regulating brain temperature, according to a new study.
A study led by Andrew Gallup, a postdoctoral research associate in Princeton University`s Department of Ecology and Evolutionary Biology, is the first involving humans to show that yawning frequency varies with the season and that people are less likely to yawn when the heat outdoors exceeds body temperature.
This suggests that yawning could be a natural brain-cooling mechanism, Princeton University and University of Arizona researchers reported.
Gallup and his co-author Omar Eldakar documented the yawning frequency of 160 people in the winter and summer in Tucson, Ariz., with 80 people for each season.
They found that participants were more likely to yawn in the winter, as opposed to the summer when ambient temperatures were equal to or exceeding body temperature.
The researchers concluded that warmer temperatures provide no relief for overheated brains, which, according to the thermoregulatory theory of yawning, stay cool via a heat exchange with the air drawn in during a yawn.
They recorded yawning frequency in 160 people in summer and winter in Tucson, Ariz., 80 for each season.
They found that nearly half of participants yawned in winter, opposed to less than a quarter in the summertime.
The study has been published in the journal Frontiers in Evolutionary Neuroscience.