Arquivos de Neuro-Psiquiatria
Print version ISSN 0004-282X
ALOE, Flávio. Yawning. Arq. Neuro-Psiquiatr. [online]. 1994, vol.52, n.2, pp. 273-276. ISSN 0004-282X. http://dx.doi.org/10.1590/S0004-282X1994000200023.
The ubiquitousness of normal yawning and the existence of abnormal yawning warrant an understanding of this reflex. Its mechanisms and functional role are not entirely known. A review of the literature reveals that yawning is a brain stem arousal reflex with both peripheral and central loops subserving reversal of brain hypoxia or hypoxemia. Behaviorally, yawning is a semi-involuntary act that occurs also because of loss of interest in the surroundings and it is not necessarily associated with fatigue. Socio-environmental factors can influence the emergence of yawning. Dopaminergic, acetylcholinergic, ACTHergic and oxytocinergic systems are involved in the generation and modulation of yawning in animal experimentation.
Keywords : yawning; fatigue; drowsiness; brain hypoxia; dopamine; acetylcholine; ACTH; oxytocin.