Yawning is a stereotyped normal behaviour with unknown physiological role. It can occur in excess due to a large variety of medical conditions. Acute bouts of yawning are an early but unspecific warning sign for upcoming disorders of consciousness or clinical worsening, which should prompt the clinician to be prepared for supportive measures. Chronic excessive yawning may lead to medical consul...

Yawning is a reflex or event that is not fully understood. It is controlled by many neurotransmitters and neuropeptides and can be induced pharmacologically by cholinergic or dopaminergic agonists. Amongst their many actions, cannabinoids acting on cannabinoid (CB(1) or CB(2)) receptors can alter cholinergic and/or dopaminergic activity. This study examined the effects of Delta(8)-tetrahydrocan...

The effects of microinjection of histamine into the paraventricular nucleus (PVN) of the hypothalamus on yawning responses were investigated in anesthetized, spontaneously breathing rats. Yawning responses were evaluated by monitoring the intercostal electromyogram (EMG) as an index of inspiratory activity and digastric EMG as an indicator of mouth opening. We also recorded the electrocorticogr...

It has long been known that the intracerebroventricular administration of ACTH1-24 increases the duration of grooming episodes and the frequency of yawning in rats. The objective of this study was to investigate in what way these episodes are prolonged and whether and to what extent genotype influences such effects. We compared the effect of increasing doses of intracerebroventricular injection...

Over the past 5 years numerous reports have confirmed and replicated the specific brain cooling and thermal window predictions derived from the thermoregulatory theory of yawning, and no study has found evidence contrary to these findings. Here we review the comparative research supporting this model of yawning among homeotherms, while highlighting a recent report showing how the expression of ...

This study was made to separate genetic from postnatal maternal influences on yawning in two strains of Sprague-Dawley rats selected for high- (HY) and low-yawning frequency (LY). Foster mothers of the two strains reared litters of pups in the four possible combinations and yawning was recorded in a novel environment when the adult offspring were 75-day-old. Yawning frequency of males and femal...

Low risk, premature infants between 30 to 35 weeks post-conceptual age (PCA) residing in an neonatal intensive care unit environment were observed in the home incubator for spontaneous yawning from 2400 to 0500 hr. Videorecordings were analyzed for the behavioral states of quiet sleep (QS), active sleep (AS), wake (W), and drowse (D) in 3-min epochs as well as the contextual behaviors before an...

Yawing was induced by microinjections of L-glutamate, cyanide and a nitric oxide-releasing compound (NOC12) into the paraventricular nucleus of the hypothalamus (PVN) in anesthetized, spontaneously breathing rats. To evaluate physiological aspects of yawning, we monitored intercostal electromyogram (EMG) as an index of inspiratory activity, digastric EMG, blood pressure and electrocorticogram (...

One of the most common signs of tiredness or fatigue is yawning. Naturally, identification of fatigued individuals would be helped if yawning is detected. Existing techniques for yawn detection are centred on measuring the mouth opening. This approach, however, may fail if the mouth is occluded by the hand, as it is frequently the case. The work presented in this paper focuses on a technique to...