Chewing on gum alleviates chronic bouts of excessive yawning: two case studies

Abstract

Spontaneous yawning is an involuntary reflex that occurs across mammals and other vertebrate classes, but the complete neurological basis of this response remains unknown.Recent studies examining the variables that alter contagious yawning in humans have provided critical insights into the mechanisms controlling spontaneous yawning, which in turn have the potential to generate applied therapeutic benefits to individuals experiencing abnormal yawning. This report details the case histories of two individuals with chronic and debilitating bouts of excessive yawning in the absence of sleep problems or any underlying medical condition to explain their symptoms. Although neither individual has received treatment to reduce their yawning, both report that chewing on gum, which has previously been shown to diminish yawn contagion in the laboratory, is effective at immediately alleviating their symptoms. In addition, one of the individuals reports that chewing on gum regularly throughout the day has diminished the overall frequency of these excessive yawning episodes. These findings are discussed in relation to research indicating that yawns function to promote neurovascular circulation and brain cooling.

The evidence does not support long-term oxygenation as a functional explanation for the evolution of yawning

“…Table 1 Other documented effects that cannot be explained by the airway hypothesis (1) The influence of nasal vs. oral breathing and carotid artery and forehead temperature on yawn frequency [23,24] (2) The link between yawn duration and brain size after accounting for body size [5] (3) How chewing on gum decreases, rather than increases, yawning [25,26] (4) The connection between abnormal yawning and thermoregulatory dysfunction in the absence of breathing problem [27] (5) Why there is a reduction in yawning frequency with senescence [28], as airway mechanics and lung function decline with age [29] (6) The fact that fish, which have a completely different oxygenation system, also yawn [30]…”