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

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Human Ethology 35(2020): 67-74
Brief report
CHEWING ON GUM ALLEVIATES CHRONIC BOUTS OF
EXCESSIVE YAWNING: TWO CASE STUDIES
Andrew C. Gallup
SUNY Polytechnic Institute, Utica, New York, USA!
a.c.gallup@gmail.com
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.
Keywords: behavioral medicine, contagious behavior , thermoregulatory dysfunction
__________________________________________________________"
Gallup, A .C. (2020). Chewing on gum alleviates chronic bouts of excessive
yawning: two case studies. Human Ethology, 35, 67-74. https://doi.org/10.22330/
he/35/067-074
submitted: 03. Aug. 2020; revised: 14. Aug. 2020; accepted: 18. Aug. 2020

Gallup, A.C (2020). Yawning Case Study
Human Ethology, 35, 67-74
INTRODUCTION
Yawning is characterized by an involuntary and extended gaping of the jaw with deep
inspiration, followed by a brief period of peak muscle contraction and then a passive
closure of the jaw with shorter expiration (Barbizet, 1958). Yawns are widespread across
mammals and other vertebrate classes (Baenninger, 1987), and have long garnered
interest in human ethology as a stereotyped action pattern and releasing stimulus
(Provine, 1986).
Nonetheless, yawning remains poorly understood and misconceptions about sleep
and oxygen are common (Walusinski, 2010a). While yawn frequency is highest just after
waking and prior to sleep onset (Provine, Hamernik, & Curchack, 1987a; Zilli, Giganti,
& Salzarulo, 2007), and is therefore correlated with subjective ratings of sleepiness
(Giganti, Zilli, Aboudan, & Salzarulo, 2010), the number of times a person yawns each
day is not related to sleep duration (Baenninger, Binkley, & Baenninger, 1996). In
addition, experiments have confirmed that the function of yawning is not to increase
blood oxygenation, and that breathing and yawning are controlled by separate
mechanisms (Provine, Tate, & Geldmacher, 1987b). Instead, yawning is a complex reflex
involved in behavioral and neurological transitions.
To date, comparative and neurological research suggests that spontaneous yawning
plays a role in promoting cortical arousal (Baenninger, 1997) and state change (Provine,
2005). Mechanistically, this is thought to occur through the changes in neurophysiology
that result from the motor action pattern. In particular, the extending gaping the jaw and
deep inhalation of air that characterizes yawning facilitates intracranial circulation
(Walusinski, 2014) and cooling of the brain (e.g., Gallup, Miller, & Clark, 2011; Shoup-
Knox, Gallup, Gallup, & McNay, 2010). From an evolutionary perspective, these
physiological processes are thought to represent the primitive function of this response,
while yawns that are released through contagion are a more recently derived feature
among highly social species (Gallup, 2011).
Studies examining the variables that alter the expression of contagious yawning,
which is often used as a proxy for spontaneous yawning since it can be reliability induced
with yawn stimuli (Provine, 1986), provide support for these physiologic interpretations.
For example, methods of behavioral brain cooling, such as nasal breathing and forehead
cooling, practically eliminate yawn contagion in the laboratory (Gallup & Gallup, 2007).
An extension of this work also showed that cooling of the carotid blood supply, which is
sufficient to decrease temperature at the superiomedial orbital area (i.e., the brain
temperature tunnel; Abreu, Haddidan, Hott, Assis, & Silverman, 2010), significantly
diminishes both the urge to yawn and overall contagious yawning frequency (Ramirez,
Ryan, Eldakar, & Gallup, 2019). Moreover, Gallup & Engert (2019) recently
demonstrated that chewing on gum significantly decreases the rate, frequency, and
duration of contagious yawning among college students. Given that the mandibular
contractions of gum chewing increase cerebral blood flow (Hasegawa, Ono, Hori, &
Nokubi, 2007), these results further support the hypothesized brain cooling and
neurovascular circulatory functions of spontaneous yawning.
Clinical findings are also in line with these interpretations. Collectively, modified
patterns of spontaneous yawning are consistently linked with medical conditions that
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Gallup, A.C (2020). Yawning Case Study
Human Ethology, 35, 67-74
alter brain temperature and/or intracranial circulation (Gallup & Gallup, 2008; Gallup,
Feo, & Gallup, 2010). In particular, excessive or abnormal yawning, which can be
defined by ≥3 yawns/15 min, has been associated with various pathologies that have
these outcomes, including stroke, traumatic brain injury, and neurodegenerative disease
(Daquin, Micallef, & Blin, 2001; Gallup, 2014; Krestel, Bissetti, & Walusinski, 2018).
Although rare, cases of chronic and debilitating bouts of excessive yawning have been
documented in the absence acute medical changes, sleep problems, or evidence for any
underlying disease. Specifically, Gallup & Gallup (2010) reported on two individuals
with analogous symptoms, each regularly experiencing bouts of uncontrollable yawning
that lasted anywhere from 5 to 45 minutes in length and could occur up to 15 times a
day. Despite each person seeing multiple doctors about their problem, neither had been
accurately diagnosed or treated effectively. Through an evaluation of their medical
histories, it was evident that changes in brain and body temperature were tied to the
onset and severity of their abnormal yawning. Moreover, both individuals reported relief
from their symptoms when implementing methods previously shown to reduce
contagious yawning in the laboratory, e.g., nasal breathing and forehead cooling (Gallup
& Gallup, 2007).
Here, the case histories of two new individuals with similar symptoms of chronic and
uncontrollable bouts of excessive yawning are reported. Just like the earlier cases, neither
individual has trouble sleeping, nor have they received a medical diagnosis to explain
their abnormal yawning. In an attempt to offer therapeutic benefits, both were provided
with a list of variables known to inhibit yawning in the laboratory through temperature
regulation and neurovascular circulation.
METHODS
Two individuals independently contacted the author by email seeking more information
about their longstanding and recurring experiences with bouts of excessive yawning.
Both were born in the United States, are college educated, married, and have children.
Each individual was asked to describe their symptoms and to provide their medical
histories regarding their condition. The local university institutional review board
approved this research and both individuals gave consent to participate in this study.
Case 1!
The first person to contact the author was a 75-year-old woman. She is 1.55 m tall and
weighs 46 kg. She reports that her bouts of excessive yawning started roughly 10 years
ago, and that her symptoms have not changed in severity. She describes herself as healthy
and her previous medical history only includes osteopenia. She has no sleep problems,
and typically sleeps 6-7 hours each night. She indicates that her yawning episodes do not
typically occur just before or after sleep, and the amount of sleep she gets is not related to
the frequency or severity of her symptoms. She has not sought direct medical advice for
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Gallup, A.C (2020). Yawning Case Study
Human Ethology, 35, 67-74
her yawning, nor is she aware of any drugs or medications she has taken that alter her
yawning.
Case 2!
The second person to contact the author was a 68-year-old man. He is 1.70 m tall and
weighs 78 kg. He reports that his bouts of excessive yawning began 17 years ago, and
since then there have been no changes in the severity of his symptoms. His previous
medical history includes appendicitis when he was a young child, three kidney stones, a
minor ischemic stroke that occurred seven years ago, and anxiety and depression 3-4
years ago. He has been taking medications for high blood pressure and high cholesterol
for ten years. He has no trouble sleeping, and typically sleeps for 7 hours each night. He
indicates that his yawning episodes do not typically occur just before or after sleep,
and that the amount of sleep he gets the night before is not related to the frequency or
severity of his symptoms the next day.
He has never sought medical assistance for his symptoms, though he has discussed
his yawning with a neurologist following his stroke, and with his general practitioner
on different occasions. He has not been prescribed any medications or treatment, nor
is he aware of any drugs of medications he has taken that affect his symptoms. His
general practitioner suggested he might have sleep apnea, which he was tested for and
diagnosed with five years ago. He states that he no longer uses a CPAP device, but
instead sleeps in a recliner, which has attenuated the heavy snoring and wake-up
drowsiness he previously experienced. No changes in yawning were reported
alongside the introduction or discontinuation of the CPAP.
RESULTS
Both individuals experience analogous symptoms. The woman reports that each bout
lasts between 10-15 minutes in length and can include 25 or more yawns. The man states
that his bouts range from 8 to 13.5 minutes in length and typically consist of 12-20
consecutive yawns. Both report that the yawns during these episodes are considerably
longer and more intense than isolated spontaneous yawns, and the woman states that
these episodes are accompanied by significant tearing from her eyes. The man indicates
that he begins to feel extremely tired during the episodes and needs to stop what he is
doing until the bout ends. The woman reports experiencing these yawning bouts
roughly five times each week, while the man experiences these bouts one to five times
daily. Neither individual is able to predict the onset of their yawning, though the woman
reports that the episodes are most frequent for her when sitting while the man indicates
that his occur predominately in the late afternoon and early evening.
Upon contacting the author, both individuals were informed of the following
variables that have been documented to reduce contagious yawning among healthy
participants in the laboratory: repeated nasal breathing, cooling of the forehead and/or
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Human Ethology, 35, 67-74
neck, and chewing on gum. Prior to even receiving this information, the woman
independently reported that chewing on gum was the only thing she was aware of that
alleviated her yawning. She reports routinely chewing gum roughly five minutes after a
bout begins, which immediately stops the yawning. Similarly, she also indicates that
sometimes eating can halt a bout of yawning. The man was not aware of any behavioral
methods to reduce his symptoms, but stated that he began chewing on gum after
receiving this information. Similar to the woman, he reports that once he begins chewing
on gum during a bout his yawning immediately stops. As a result, he has started chewing
on gum regularly throughout the day, and since doing so has noticed that the frequency
of these newly abbreviated bouts has even diminished. Instead of experiencing one to
five distinct bouts of excessive yawning per day, he now experiences only one or two
episodes daily. Neither patient reported implementing other behavioral measures.
DISCUSSION
Most people yawn between 5 and 10 times per day (Baenninger et al., 1996; Walusinski,
2010b), with these events clustered during transitional periods of sleeping and waking
(Provine et al., 1987a). However, more frequent yawning is known to be a common side-
effect of certain pharmaceutical drugs (Beale & Murphee, 2000; Gallup & Gallup, 2009),
and abnormal forms of yawning have been associated with various medical conditions
and neurological pathologies (Daquin et al. 2001; Gallup & Gallup, 2008; Krestel et al.,
2018; Walusinski, 2010).
The current report documents two new cases of chronic bouts of excessive yawning
that have not been linked to changes in health status, an underlying medical condition, or
drug use. Both individuals report that their abnormal yawning originated ten or more
years ago. The bouts they experience include 12-25+ consecutive yawns, which are
described as more intense and longer in duration than typical yawns, and span 8-15
minutes in length. The woman typically experiences these bouts five times per week,
while they are triggered between one to five times daily for the man.
Previously, chronic cases of excessive yawning similar to this were found to be
associated with temperature changes and thermoregulatory dysfunction (Gallup &
Gallup, 2010). However, the information acquired from the current study does not show
a direct connection with temperature regulation. Unlike in Gallup & Gallup (2010),
neither individual here reported feeling cold during or after a long bout of yawning,
identified pharmaceutical drugs that exacerbated the condition, or had documented
changes in body temperature surrounding these events. In addition, neither individual in
the current report indicated attempting nasal breathing or forehead/neck cooling as a
means of alleviating their yawns, which were effective at reducing or postponing bouts of
yawning in the previous cases. Instead, both individuals here reported being able to
completely halt a bout of yawning by chewing on gum. The man also indicated that
chewing on gum throughout the day reduced the overall frequency of these episodes.
These findings provide converging evidence that gum chewing inhibits the
expression of yawning. Recently, Gallup & Engert (2019) found that chewing on gum
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Gallup, A.C (2020). Yawning Case Study
Human Ethology, 35, 67-74
reduced the rate, frequency, and duration of contagious yawning among college students
in the laboratory. Similar to the extended gaping of the jaw during yawning, the
mandibular contractions of chewing on gum are known to increase cerebral blood flow
(Hasegawa et al., 2007), and therefore this behavior may act to stifle the mechanism(s)
driving the abnormal yawning. Previous research has pointed to the mandibular gaping
of the yawn reflex as being essential for the proper functioning of this response. For
example, patients with tetraplegia, who cannot open their mouth voluntarily, are known
to extensively gape their jaw while yawning (Bauer, Gerstenbrand, & Hengl, 1980;
Geschwend 1977). In addition, people instructed to clench their teeth while yawning
report feeling left in mid-yawn and indicate the experience as unpleasant (Provine,
1986).
The neuroanatomical center and complete neurochemistry controlling yawning
remain unknown (Krestel et al., 2018), and therefore further studies in neuroscience and
medicine are needed to fully uncover the mechanism(s) governing this response.
However, as this work shows, non-invasive studies examining the variables that alter
yawn contagion can also be valuable in improving our understanding of this stereotyped
action pattern. Although the etiology of the chronic yawning experienced by the two
individuals here cannot be determined, this report was able to draw on findings from
basic research in psychology to demonstrate unique therapeutic benefits of chewing on
gum. Given that similar forms of chronic and debilitating bouts of excessive yawning
have been reported elsewhere, this condition may be more common than previously
recognized. Hopefully this work will help spur further examination of these symptoms
and help clear up common misconceptions about excessive yawning. To this point,
neither individual has received a diagnosis to explain their abnormal yawning or been
effectively treated by a physician to reduce their symptoms; however, both have been
notified of the possible connection to brain thermoregulation.
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