It occurs all of a sudden; sometimes out of the blue but, on many other occasions, by ‘contagion’. Yawning is a reflex action that makes us open our mouth wide open and breathe deeply for about six seconds. It’s accompanied by the stretching of the eardrums and it ends with an exhalation of breath. This isn’t anything new to you as we humans, along with most mammals, start doing it even inside the womb until we pass away. But why? What exactly does trigger yawning and, more than that, why is it so contagious?
To this day, scientists haven’t come up with solid answers to unravel the ‘mysteries’ of yawning, but there seems to be some consensus on one particular theory. And no, it doesn’t refer to the fact of being sleepy, tired or bored, as popularly believed. This hypothesis suggests that, as it happens with sweating, yawning could be another way for our body to regulate its temperature… but, in this case, to cool down our brains!
According to different researchers, there are certain processes such as the sleep cycles, cortical activation or stress that tend to heat up the brain, so yawning might help refrigerate the ‘system’ as it brings cooler blood in. The gulp of air taken in changes the temperature of the blood flow, which increases in the face, head and neck when stretching our jaws (both things happen simultaneously while yawning). The process is thought to help balance the temperature, thus promoting a good brain activity. And the reason why we usually yawn the most before going to sleep and after waking up is that these are the times of the day when our body temperature peaks, and so does the brain’s.
An (almost) endless loop
Have you already yawned while reading these lines? That would not be surprising at all since it just takes us to see, hear or read about it to start stretching our jaws once again. Actually, I’ve already done it myself a few times while typing the text! If theories regarding the function of yawning have puzzled researchers for years, it is nonetheless true that there’s an even more intriguing question related to such a reflex action: why does yawning take hold of us after being exposed to it?
A study published by the Plos One journal in 2011 determined that yawning is contagious as it has a strong emotional component. Therefore, yawns appear to be another element of social bonding or, in other words, a way for us to empathize with our fellow human beings. The key seems to lie in a perception-action correlation that makes us represent an observed behaviour through a neural mechanism. For example, if somebody smiles at us, we usually smile back, and the same may go for yawning. Such a study concluded that yawning contagion is more likely to happen when interacting with our loved ones, family and friends, whereas it doesn’t happen as often among strangers. And similar patterns have been observed in certain groups of animals, like chimpanzees.
Beyond hypothesis, definitive answers to such questions are yet to be found. Or, who knows, yawning and its contagion effect might remain an enigma forever. No matter whether we find out what’s behind it, what’s for sure is that we will be yawning day after day.
