23. Yawning Can Indicate Stress
Remember that yawning stimulates the brain to release dopamine, one of the “feel-good” hormones that help you feel pleasure. It is also a social behavior that allows you to communicate something through non-conscious means. So we shouldn’t be surprised that people who are stressed yawn more.
Perhaps their subconscious brains are trying to communicate to the people around them that there is something wrong to elicit an empathetic response. What is remarkable is that this stress aspect of yawning is not limited to humans. Dogs also may yawn as a means of indicating that they are stressed.