Why Do We Yawn?
Though we don’t know all the reasons for yawning, it is usually a way of helping our breathing. That extra deep breath gets oxygen into our bodies.
Having the urge to yawn usually means that for one reason or another, our intake of oxygen has fallen below what is needed.
The usual yawn is due to fatigue, and is a sign that the body needs sleep. We may also yawn when our bodies aren’t getting enough fresh air. Then we may need better ventilation, or exercise.
Yawning helps awaken a person by stretching the muscles and helping to get things moving again.
Other people believe that yawning is a protective reflex to redistribute the oil-like substance called surfactant that helps keep lungs lubricated inside and keeps them from collapsing.
So, if we didn’t yawn, according to this theory, taking a deep breath would become harder and harder — and that would not be good!