The capacity of four-dimensional sonography to evaluate complex facial expressions allows recognition of a common behavior, yawning. Although there has been remarkably little interest in yawning in research and medical practice, even though it is an everyday phenomenon, we submit an original interpretation on the basis of knowledge derived from phylogeny and ontogeny. As a flip-flop switch, the...

Krestel et al. (2013) recently investigated the potential contributing factors associated with abnormal yawning (defined as ≥3 yawns/15 min) in 10 patients with acute anterior circulation stroke. Though frequent yawning had previously been observed in stroke patients (Cattaneo et al., 2006; Singer et al., 2007), this study attempted to assess the influence of specific physiologic and lesion top...

This study reports the first experimental exploration of possible contagious yawning in monkeys. Twenty-two stumptail macaques (Macaca arctoides) were presented with video clips of either yawns or control mouth movements by conspecifics. At a group level, monkeys yawned significantly more often during and just after the yawn tape than the control tape. Supplementary analysis revealed that the y...

Contagious yawning is thought to represent a basic form of empathy involved in state matching. Despite recent evidence in support of this connection, the neurochemical basis of contagious yawning remains largely unknown. Here, we investigate whether intranasal oxytocin, a hormone and neuropeptide involved in empathic processing, bonding and social affiliation, influences contagious yawning amon...

Excessive yawning was described in some neurological conditions as part of periictal or ictal manifestations of epilepsy, most commonly temporal lobe. We present the first case of controllable yawning as a primary seizure semiology with dominant frontal lobe involvement in a 20-year-old man. Video electroencephalography recorded 8 yawning episodes accompanied with right arm movement correlating...

An elderly hemiplegic patient participating in an EMG biofeedback training program was observed to produce a synergistic flexion movement of the plegic (determined by functional evaluations) upper limb while yawning. In the course of the training sessions the electrical activity of the anterior deltoid (the target muscle) was recorded during yawning. These peak EMG values were greatly facilitat...

Yawning is a scientific conundrum that has baffled scientists for decades. Whilst the origin and mechanism of yawning may be understood, its presence and frequency in a number of neurological disorders is not clearly understood. The Thompson Cortisol Hypothesis (2011) proposes a link between yawning and blood cortisol levels because of the known association between cortisol (and its elevation i...

The contagious aspect of yawning is a well-known phenomenon that exhibits variation in the human population. Despite the observed variation, few studies have addressed its intra-individual reliability or the factors modulating differences in the susceptibility of healthy volunteers. Due to its obvious biological basis and impairment in diseases like autism and schizophrenia, a better understand...

The biomedical hypothesis proposed here is that the immediate trigger for a yawn is a restricted collapse of a few alveoli in the lungs. The extent of this alveolar collapse may be too small for it to be detected by current X-ray technology, but this technology is continually improving and may soon be good enough to test the hypothesis. In support of the hypothesis, it is shown that yawning can...