Even thinking about yawning can provoke the urge. As irrepressible as it is contagious,1-3 yawning benefits the yawner (which includes practically all vertebrates)4 in a variety of neurologic, homeostatic and musculoskeletal ways.5
Yawning prepares an individual for an upcoming event or behavioral transition. It tenses the neck, compresses the carotid body and stimulates the sympathetic nervous system.6 In so doing, it increases facial temperature, lung volume and heart rate. A faster heart rate fuels the brain with faster blood flow to and fro, creating convective cooling.7 This helps explain why migraineurs and those with thermoregulatory disorders yawn more frequently.
The urge to yawn shares some brain territory overlap with other events characterized by either an urge or a desire for action.”8 That is, whether one feels impelled to yawn, swallow or urinate, the urge arises in the sensory and motor regions of the limbic system, specifically the insula and mid-cingulate cortex.
Developmental neurophysiologists are asking whether it might be possible to predict brain dysfunction of fetuses in utero given that it has become possible to observe complex facial expressions such as yawning, through four-dimensional sonography.9 Ex utero, those afflicted with autism spectrum disorders show disturbances in contagious yawning.10-12 A question for comparative behaviorists might be whether dogs with neurobehavioral problems also exhibit deficits in contagious yawning.
Prelude to Yoga Poses
The natural sequence of a yawn can encompass the entire body, if allowed to do so. It may precede a specialized subset of involuntary stretching behaviors that occur across species. These movements, known as “pandiculation,” illustrate ways in which an individual expresses a highly orchestrated sequence of involuntary acts, often associated with the yawn.
Consider the uninhibited office worker who, for example, after long periods arched over a desk, exhibits the full yawn-stretch repertoire. The neck and back arch, arms and legs extend, and joints perform movements that unlock the closed, hunched, and bent posture the body had been held within. As the mouth opens wide, the eyes tend to close, the breath draws in deeply, and the worker may vocalize in utter enjoyment of the physical reawakening.
Awareness becomes intero-rather than exteroceptive. Touching the pandiculating person to gain their attention is ill advised; the muscles are undergoing eccentric and vigorous contraction. Interrupting this sequence may invite ire and pain, as the person is in the throes of a modal action pattern (an orderly sequence of reflexive behaviors) that is serving to reset muscle tone and length.
Even a politely executed yawn at, for example, a board (or bored) meeting is difficult to suppress. Individuals attempt to restrain their pandiculation as much as possible, poising their hand in front of the mouth and maintaining a stiff posture.
In contrast, most of us have witnessed the compelling yogic display of a young and limber dog or cat arising from a nap. Ears flex back, eyes close and they assume a yoga posture appropriately termed “downward dog.” This popular asana makes a triangle of the upper and lower body with the ground.
Small animals perform this naturally and embellish upon it as they reach forward with one, then the other, paw, with a spinal extension that many yoga aficionados strive to emulate.
A dog or cat may follow the downward-facing dog with its upward-facing counterpart, reversing the flexion of the hips with full extension throughout. These postures stretch and reinvigorate the spine and appendages, eliminating restraints and restrictions on movement that built up while sleeping or performing the activities of daily living.
Most animals, including humans, tend to yawn and stretch less completely as they age. For people, cultural conditioning inhibits pandiculating in public.13 Pandiculation provides fertile ground for pain and movement research.
One might ask: Do pain and habitual postural changes inhibit or eliminate the ability of dogs and cats to perform a full-body pandiculation? How does incremental loss of the stretch-yawn syndrome impact body-mind homeostasis?14 Given that pandiculation resets the central nervous system as it transitions between cyclic biologic behaviors, including the sleep-wake rhythm,15 might the ability to yawn and stretch become barometer of whole body function?16
The stretch-yawn syndrome (SYS) maintains mobility of the myofascia. Sleeping and long periods of immobility predispose the soft tissues to cross-linking of collagen. This “tying up” of tissue diminishes function by limiting tissue length and strength.
It reduces the freedom of muscle groups to glide past one another for optimal motor function. Counteracting cross-linking “undoes” impediments to movement that set in during rest and suboptimal movement. Purposefully restoring the ability to stretch and facilitating involuntary motion sequences of pandiculation may confer the capacity for individuals to keep their structures flexible day in and day out.
Doggie yoga, anyone?
For those who have lost touch with safe and effective pandiculation, Bertolucci describes a new technique called “muscle repositioning,” a form of myofascial release that elicits involuntary motor reactions designed to restore structural and segmental integration.17
Improper pandiculation can lead to problems. For example, the first report of a rib fracture caused by a morning yawn was reported recently in The Journal of Emergency Medicine.18 A 13-year-old boy experienced a sudden, sharp and stabbing pain in his left shoulder and neck after pandiculating in the morning after waking. As he yawned and stretched, he turned his head toward the right and heard a click in the neck; radiographs revealed a fracture of the first rib.
Simultaneous, eccentric contraction of the scalenus anterior, scalenus medius and serratus anterior muscles may have produced a shearing force at the most narrow portion of the first rib where a groove allows for passage of the subclavian artery. The teenager awoke, according to his mother, with his right arm flexed and pointed upward while his left arm was outstretched and pointing down.
Yawn, and Pass It On
From a public health perspective, and considering all the things that we can catch and pass on to one another, the yawn and urge to stretch contagion seems like a blessing from Nature. This unspoken, irresistibly strong reminder to breathe, stretch and integrate the body and mind spreads unconsciously and effortlessly from one individual to another, crossing boundaries of age, species and station in life.
Now, please pardon me while I pandiculate.
Dr. Robinson, DVM, DO, Dipl. ABMA, FAAMA, oversees complementary veterinary education at Colorado State University.
2. PLatek SM. Yawn, yawn, yawn, yawn; yawn, yawn, yawn! The social, evolutionary and neuroscientific facets of contagious yawning. Front Neurol Neurosci. 2010;28:107-112.
3. Miller ML, Gallup AC, Vogel AR, et al. Evidence for contagious behaviors in bugerigars (Melopsittacus undulatus): an observational study of yawning and stretching. Behav Processes. 2012;89(3):264-270.
6. Matikainen, J., and Elo, H. (2008). Does yawning increase arousal through mechanical stimulation of the carotid body? Med. Hypothesis 70, 488–492. Cited in: Corey TP, Shoup-Knox ML, Gordis EB, et al. Changes in physiology before, during, and after yawning. Frontiers in Evolutionary Neuroscience. 2011;3:7. Epub 2012 Jan 3.
11. Senju A, Maeda M, Kikuchi Y, et al. Absence of contagious yawning in children with autism spectrum disorders. Biol Lett. 2007;3(6):706-708.
12. Helt MS, Eigsti IM, Snyder PJ, et al. Contagious yawning in autistic and typical development. Child Dev. 2010;81(5):1620-1631.
17. Bertolucci LF. Muscle Repositioning: Combining subjective and objective feedbacks in the teaching and practice of a reflex-based myofascial release technique. International Journal of Therapeutic Massage and Bodywork. 2010;3(1):26-35.