A yawn is a reflex conseestin o the simultaneous inhalation o air an the stretchin o the eardrums, follaed bi an exhalation o braith.

Yawn
Joseph Ducreux pandiculatin (baith yawnin an stretchin); sel-portrait c. 1783
OrganismsVertebrates
Biological seestemNervish seestem
HealUnaffectit or benefeecial
ActionInvoluntar
StimuliFatigue
Boredom
Stress
Sleepiness
Ithers mirror neuron reflex
MethodComplete extension o jaw, inhalation, een close, stretchin o he eardrum, exhalation
Duration8 seiconts