Why do we yawn and why is it contagious?
May 21, 2018 by Mark Schier And Yossi Rathner, The Conversation
Consider the scenario. You're driving on a long, straight stretch of country highway at about 2pm on a sunny afternoon, and you're desperately keen to reach your destination. You're trying to stay alert and attentive, but sleep pressure is building up.
In response you yawn, sit up straighter in your seat, possibly fidget around a little and engage in other mannerisms that may increase your level of arousal.
https://medicalxpress.com/news/2018-05-contagious.html
