title: Why do we yawn?
abstract: Yawning is a phylogenetically old behaviour that can be observed in most vertebrate species from foetal stages to old age. The origin and function of this conspicuous phenomenon have been subject to speculations for centuries. Here, we review the experimental evidence for each of these hypotheses. It is found that theories ascribing a physiological role to yawning (such as the respiratory, arousal, or thermoregulation hypotheses) lack evidence. Conversely, the notion that yawning has a communicative function involved in the transmission of drowsiness, boredom, or mild psychological stress receives increasing support from research in different fields. In humans and some other mammals, yawning is part of the action repertoire of advanced empathic and social skills.
authors.affiliation: University of Geneva, Department of Clinical Neurosciences, Division of Neurorehabilitation, Avenue de Beau-Séjour 26, Geneva 14, Switzerland. aguggis@gmail.com
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Guggisberg
authors.forename: Johannes
authors.initials: J
authors.lastname: Mathis
authors.forename: Armin
authors.initials: A
authors.lastname: Schnider
authors.forename: Christian W
authors.initials: CW
authors.lastname: Hess
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D001143:Arousal / Q000502:physiology*; D001833:Body Temperature Regulation / Q000502:physiology; D001921:Brain / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D010101:Oxygen Consumption; D012919:Social Behavior; D015000:Yawning / Q000502:physiology*