You yawn when you see someone else yawning?
Is yawning really contagious?
People yawn because they get rid of the amount of carbon dioxide in their lungs.
Therefore, it is said that you will want to yawn if you are in a room with a high carbon dioxide concentration.
In addition, it has the effect of adjusting the air pressure in the ears and promoting the secretion of saliva and tears.
In other words, it is difficult to identify the cause of yawning every time.
There are also reports that there is no correlation between carbon dioxide concentration and yawning frequency.
The cause of yawning feeling contagious is likely to be mere empathy.
– Healthline: Why Do We Yawn and Is It Contagious?