Why is yawning infectious? First let’s see how we define a yawn. Yawning can be defined as a sudden, deep inhalation of air accompanied by an open mouth, tightened cheek muscles, eye closure, and tearing. Everybody yawns -from unborn babies to the oldest human being. Animals do it, too. And before you finish reading this, it's likely that you will end up yawning at least once, if not more. Why? I will come to that later.
But, why exactly do people and animals yawn? Science and researches haven’t yet reached a conclusion. But there are several theories or ideas about why people yawn. Here are the few most common theories. One theory says that our bodies induce yawning to draw in more oxygen or remove a build-up of carbon dioxide. According to another theory, which is also the most popular one, yawning is said to be caused by boredom, fatigue or drowsiness. Again there’s a theory which believes, yawning is a protective reflex to redistribute the oil-like substance called surfactant that helps in keeping lungs lubricated inside, saving them from collapsing. According to the evolution theory - yawning is something that began with our ancestors, who used yawning to show their teeth to intimidate others. An offshoot of this theory is the idea that yawning developed from early man, was a signal for others to change their activities.
But there is one idea about yawning that everyone knows to be true -yawning is contagious by nature. If you yawn in a meeting, you'll probably notice a few other people have started yawning, too. Even thinking about yawning can get you yawning. Scientists explain the "contagious" nature of yawning as, the power of suggestion, that is, when one person's yawn triggers another nearby to yawn.
How many times have you yawned while reading this article? Have I provoked a yawn out of you yet? If I have, it’s by the power of suggestion! Just as seeing or hearing someone else yawn makes you yawn, reading about yawning may also make you yawn. Honestly, even I have yawned a few times while writing this –such is the infectious nature of yawn!