Pay attention to it. Even if you are rested, you have slept well and you are not even hungry, in the summer the yawn comes unexpectedly more often than in the cold months. The reason? The higher temperatures to which our body must, with difficulty, adapt. A study published in Physiology & Behavior and conducted by a group of scientists from Tucson (USA) and Vienna (Austria) on unsuspecting inhabitants of their respective towns, he described yawning as a self-regulating mechanism of brain temperature.
even the brain is hot. Analyzing the spontaneous yawns of passers-by and crossing the data with the weather variables, the researchers found a higher frequency in correspondence with temperatures between 20 ° and 25 °. The yawn, in other words, would serve to cool the brain (which works best below 20 °), thanks to the increased blood flow caused by ingesting more air. However, the mechanism does not trigger with temperatures above 37 °, probably because it would be ineffective given the excessive thermal difference.
The function of yawning – a reflex, that is, involuntary breathing act – commonly associated by scientists also with fatigue, boredom, hunger and even imitative mechanisms, is not yet very clear, even if it is hypothesized that it is a means by which the organism seeks to react to a state of numbness and to regain a state of alertness, thanks to the increased influx of oxygen into the blood and from there to the brain.
How yawning works. During the yawn, in the inhalation phase, a sequence of movements is carried out that have the purpose of facilitating the passage of air: the mouth is opened, with contraction of the muscles of the face, the glottis is raised, freeing the passage of air in the trachea, the rib muscles contract, causing the thoracic cavity to rise and widen and the diaphragm to distend. The exhalation of the air, more superficial than the inhalation, sees the progressive return to the initial position, with the rapid expulsion of the introduced air.