- Andrew
C. Gallup. Yawning and the thermoregulatory
hypothesis
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- Gallup and Gallup recently described two
independent case histories of women who suffer
from recurrent, debilitating bouts of excessive
yawning. Based on past research showing an
association between yawning and thermoregulation
and clear symptoms of thermoregulatory
dysfunction among these women, it was suggested
that the trigger for excessive yawning may be
due to increases in brain and/or body
temperature. Elo has challenged this report,
suggesting there were problems concerning data
collection and conclusions drawn from it.
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- Elo argues that, since the authors did not
personally meet these patients, the reports are
"only" subjective and may be unrelated.
Obtaining information regarding medical
histories and symptoms through face-to-face
interviews is neither a necessary or sufficient
condition for obtaining relevant information.
Indeed, it could be argued that the objectivity
of investigators who personally meet and
interact with their subjects may, in fact, be
unwittingly compromised as a consequence.
Suffice it to say that we encouraged the
patients who contacted us to respond to a
battery of questions about their symptoms and
medical histories, and the behavioral symptoms
of one patient were observed through a video
that was shared with the authors. It is also
important to note that the authors and the
patients engaged in a detailed series of
internet communications about their condition
that extended over a period of months. Moreover,
considering that a yawning attack would likely
be absent during a personal visit, the sum of
information obtained by Gallup and Gallup in all
likelihood exceeds that obtained by past
physicians.
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- As for the notion that these cases may be
unrelated, the results clearly illustrate a
striking number of consistencies. Each patient
complains of unpredictable and uncontrolled
yawning attacks that last from 5 to 45 min in
length and can occur between one to 15 times per
day. These episodes are characterized by both
women as involving repeated deep and
overwhelming yawns that cause their eyes to
water and their noses to run. Both women also
report feeling cold during or after each bout of
excessive yawning, experiencing goose bumps and
shivering. In each case, these attacks disrupt
normal activity and produce adverse and
debilitating side effects (e.g., ill feeling,
exhaustion). Finally, each patient has sought
the advice of numerous physicians, none of whom
have been able to properly diagnose or
effectively treat their symptoms. Indeed, both
patients expressed concern that their problems
were not always taken seriously by their
physicians and, on occasion, felt they were
subject to ridicule rather than assistance.
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- Elo also attempts to dismiss
thermoregulatory dysfunction on the grounds that
each woman received sleep-related diagnoses.
Although previous diagnoses include sleep
disorders, neither woman has experienced or
shows any form of sleep disturbance or related
fatigue, each reporting that they consistently
get 7-8 h of sleep a night. Past diagnoses of
sleep problems have either been completely ruled
out (narcolepsy and daytime sleepiness in
patient 1) or corrected (sleep apnea in patient
2); yet, their yawning problems persist.
Therefore, it seems abundantly clear that each
woman does, in fact, suffer from excessive
yawning in the absence of sleep problems. Elo
also contends that proper attention was not
given to certain aspects of each medical
history. It is important to note, however, that
all conclusions drawn from the medical histories
were based on confirmed reports from past
physicians. For instance, insulin resistance in
patient 1 was not deduced from the information
provided to the authors (as suggested by Elo),
but instead, was independently diagnosed by a
physician through medical examination.
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- Elo further states that both patients should
seek medical assistance for their condition. In
fact, we encouraged each patient to continue to
pursue medical advice on several occasions. Elo
appears to ignore the fact that, as described in
the report, each woman has seen multiple
physicians about their problem. Patient 1 has
sought assistance from 13 different doctors,
while patient 2 has seen fout It is because
neither woman has been properly diagnosed or
effectively treated that they independently
sought our attention in the first place. In no
way were our interpretations conveyed as
providing defmitive conclusions or as
substitutes for medical diagnoses. Based on the
information obtained from these case reports,
however, each patient has recognized new
behavioral methods (e.g., nasal breathing and
forehead cooling) for better coping with their
problem on a daily basis.
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- The remainder of the response by Elo refers
to the temperature measurements taken by patient
2, as if our conclusions would stand or fall as
a consequence. In fact, we view these
measurements as being only one small bit of
evidence against a backdrop of other indications
suggesting thermoregulatory dysfunction. We
realize that it is possible that the oral
temperature measures do not reflect actual brain
or body temperature. Likewise, the accuracy
(±) of the digital thermometer was not
available. But, it is not a question of the
absolute values per se, rather the differences
that were obtained across repeated measures.
None of these concerns detract from the fact
that nine out of ten measurements revealed a
reduction of oral temperature immediately
following an attack, and both women report
feeling cold during or after attacks,
experiencing goose bumps and shivering. These
data are indicative of significant temperature
decreases surrounding these yawning episodes,
and this is entirely consistent with the
thermoregulatory hypothesis. The anticipation of
yawning attacks is obviously based on subjective
impressions of the patient, and the intermittent
nature of these episodes would make more
controlled recordings difficult to obtain.
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- To provide more insight into the nature of
these yawning attacks, the video provided by
patient I was further analyzed. Although this
was not the same woman to provide the initial
temperature recordings, the consistency in the
description of each of their symptoms warrants
comparison. In a period of 2 min and 40 s, this
woman yawned a total of eight times with each
yawn lasting an average of 7.25 s. In other
words, over 1 out of every 3 s (58/160) was
spent yawning, and yawns were longer than
average duration. Each yawn consisted of
powerful jaw, neck, and body stretching, and
time spent in between yawns also included deep
inhalations. Therefore, other associated and
significant respiratory and cardio-vascular
changes could easily have contributed to more
widespread cooling.
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- Each case reported by Gallup and Gallup is
clearly indicative of thermoregulatory
dysfunction and is consistent with past
comparative research showing an association
between yawning and thermoregulation. Both women
report that deep nasal inhalations and the
application of cool cloths to the forehead have
been effective in postponing and providing
temporary relief from these attacks. Due to
research showing that nasal breathing and
forehead cooling reduce brain temperature and
inhibit yawning, these effects are consistent
with the interpretation that excessive yawning
is triggered by rises in brain temperature.
Likewise, patient 1 reports complete remission
of symptoms when taking a cold shower or
swimming in cold water. As further evidence for
a connection between their excessive yawning and
thermoregulatory dysfunction, each woman reports
feeling cold and experiences goose bumps and
shivering during and after attacks. Lastly,
modafinil, a drug that increases body
temperature and impairs cooling responses, was
found to exacerbate yawning symptoms in patient
1.
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- Therefore, the concerns of Elo
notwithstanding, the case studies of Gallup and
Gallup do in fact suggest that the excessive
yawning experienced by these two women is a
result of thermoregulatory dysfunction. As
further support for the interpretation that
yawning is triggered by heightened brain and/or
body temperature, recent research in our
laboratory where temperature probes were
implanted in the brain shows that spontaneous
yawning in rats coincides with rapid increases
in brain temperature and is invariably followed
by corresponding decreases in temperature
immediately after each yawn (unpublished data).
In addition, recent comparative research on
budgerigars (Melopsittacus undula tus) has shown
a strong negative correlation between body
temperature and yawning latency in
handling-stressed birds. Considering the
available medical history and behavioral
evidence, temperature regulation remains the
most parsimonious explanation for the observed
symptoms in both of these women.
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