+A yawn is an involuntary reflex characterized by widely opening the mouth and taking a deep breath, often associated with [Sleep](/wiki/sleep) or tiredness. This ancient behavior can be surprisingly [Contagion](/wiki/contagion), spreading easily from one individual to another.
+## See also
+- [Breathing](/wiki/breathing)
+- [Fatigue](/wiki/fatigue)
+- [Reflex](/wiki/reflex)
... 1 more lines