Why do we yawn when
- why do we yawn when working out
- why do we yawn when cold
- why do we yawn when hungry
- why do we yawn when we pray
- why do we yawn when bored
- why do we yawn when weu0026#39;re tired
- why do we yawn when sleepy
- why do we yawn when we are sleepy or drowsy
- why do we yawn when we are tired
- why do we yawn when others yawn
