Source: Wikipedia, the free encyclopedia.
Close-up of a newborn baby girl yawning while lying down
A yawn is a reflex consisting of the simultaneous inhalation of air and the stretching of the eardrums, followed by an exhalation of breath. Many animal species, including birds and fish, experience yawning. The study of yawning is called chasmology. Yawning (oscitation) most often occurs in adults immediately before and after sleep, during tedious activities and as a result of its contagious quality. This photograph shows a newborn girl yawning; research data strongly suggest that neither contagious nor story-induced yawning is reliable in children below the age of six years.Photograph credit: Martin Falbisoner