The phenomenon of yawning is just as
intriguing and fascinating as sleep.
Understanding its causes and consequences has
defied the human mind for centuries.
Hippocrates, Sennert, Boerhaave and de Gorter
each advanced a theory in his time. From the
release of tainted humour to the activation
of animal spirits and improved brain
oxygenation, the metaphors that developed
from these theories are all characterised by
their popular success, which endured until
the time of JM. Charcot and even into our own
day.
However, starting in the early 19th
century, a neuromuscular theory developed
from the experimental physiology of Broussais
and Flourens that Dumpert, working in Germany
after World War I, explained in detail.
Experimental ethology and pharmacology in
the 20th century brought to light the
neuromediators and subcortical structures
involved in yawning and pandiculation.
Phylogenetically and ontogenetically
primitive, these motor behaviours have been
remarkably well preserved during evolution
and are nearly universal in vertebrates. They
are closer to an emotional stereotypy than to
a reflex. Originating in the diencephalon,
they appear to exteriorise homeostatic
processes in the systems controlling arousal,
hunger and sexuality.
Life, in all its aspects, has always
given rise to thought and questioning.
Explanations of physiological phenomena have
always provided us with reassurance. As noted
by HL. Mencken: "Explanations exist and have
always existed, because there is always a
simple solution to each human problem, a
clear solution that is plausible and false".
The history of knowledge on yawning is a
perfect example of this precept. The causes
and consequences of this intriguing
phenomenon, as fascinating as sleep, have
defied the human mind for centuries. The
results of this review will inevitably
highlight the numerous uncertainties that
still exist in the 21st century.
Medicine originated in antiquity, from
myth and philosophy, gradually extracting
itself from the uncertainties of magic and
religion and moving towards a rational
approach. This is illustrated below in a
survey covering several centuries.
In the tablets on Babylonian medicine
that have been deciphered, there is no
mention of yawning. Ethnomedicine, whether
focused on Asia or Africa, has not studied
yawning either.
Antiquity and the
Middle Ages
Greek philosophy has provided us with a
combination of four elements to explain the
world (earth, air, fire, water). These
elements carry the four physical qualities
(moist, dry, hot, cold) that influence the
"humours" (black bile, phlegm, yellow bile,
blood). These theories were applied in the
first medical writings on yawning, in De
flatibus liber, a treatise on wind written by
Hippocrates in 400 BC. He observed: "Yawning
precedes a fever, because the large quantity
of air that has accumulated ascends all at
once, lifting with the action of a lever and
opening the mouth; in this manner the air can
exit with ease. Like the large quantities of
steam that escape from cauldrons when water
boils, the accumulated air in the body is
violently expelled through the mouth when the
body temperature rises." As we will observe
below, this idea persisted until the 17th
century.
Discussing topics far removed from the
physics he applied to humans, Hippocrates
described jaw movement caused by yawning with
great precision in On the Articulations,
assimilating it to traumatic joint disorders.
He related a reduction procedure incorrectly
attributed to Nélaton in the 19th
century: "With regard, then, to the matter on
hand, the jaw-bone is rarely dislocated, but
is frequently slackened (partially
displaced?) in gaping, in the same manner as
many other derangements of muscles and
tendons arise. Dislocation is particularly
recognised by these symptoms: the lower jaw
protrudes forward, there is displacement to
the opposite side, the coronoid process
appears more prominent than natural on the
upper jaw, and the patient cannot shut his
lower jaw but with difficulty. The mode of
reduction which will apply in such cases is
obvious: one person must secure the patient's
head, and another, taking hold of the lower
jaw with his fingers within and without at
the chin, while the patient gapes as much as
he can, first moves the lower jaw about for a
time, pushing it to this side and that with
the hand, and directing the patient himself
to relax the jaw, to move it about, and yield
as much as possible; then all of a sudden the
operator must open the mouth, while he
attends at the same time to three positions:
for the lower jaw is to be moved from the
place to which it is dislocated to its
natural position; it is to be pushed
backward, and along with these the jaws are
to be brought together and kept shut. This is
the method of reduction, and it cannot be
performed in any other way." No further
comments are needed.
Emile Littré, who translated
Hippocrates in the middle of the 19th
century, rendered a passage on the causes of
apoplexy as follows: "The continual yawning
of apoplectics proves that air is the cause
of apoplexy". Jacques Jouanna refutes this
interpretation in his recent translation: "It
is not obvious why paralysed patients would
be affected by continual yawning. There could
be another explanation, namely that of
patients constantly having their mouths open,
which is observed in certain cases of
paralysis. The author, Hippocrates, has done
his best to fit this observation into his
explanation: the mouth stays open due to the
continual presence of an excessive quantity
of air in the body." And yet, modern medical
observations indicate how right Littré
seems to be!
Pliny the Elder noted in 40 BC that
repeated yawning, when accompanied by
extensive haemorrhaging, was a sign of
approaching death. This subject is the topic
of a thesis in Latin, De oscitatione in
enixu, written by Johannes Lapehn in 1758
under the direction of Johannes Roederer in
Göttingen. Haemorrhaging after delivery
has killed thousands of women. The drop in
blood pressure and the collapse triggered by
haemorrhaging stimulates the autonomic
nervous system. Yawning is an expression of
this system, as it is during a vasovagal
episode, and precedes loss of
consciousness.
In his letter to Lucilius, Seneca wrote
in approximately 50 AD: "Just as in weakened
subjects, disease is signalled by precursory
signs: either excessive nervousness, or a
weariness unprovoked by effort; or yawning;
or a shiver running through the limbs. In
this way a fragile soul is struck long before
illness befalls him, suffering by
anticipation and succumbing ahead of time."
Is he talking about incubation, the onset of
fever, somnolence, a depressive state?
Galen and Celsus alluded to Hippocrates
by transposing the productive effect of
yawning winds on the muscles. Following the
line of Hippocrates' observations, Oribase
wrote a chapter on causes and symptoms in 450
AD. He lumped together convulsions,
palpitations, hiccups, trismus, limb
extension and yawning: "They all belong to
the same family, which involves perversion of
muscular movements". [...] "Yawning
and limb extension are acts of nature in
which the body is forced to move violently by
some kind of morbid cause."
Starting in the 15th century, medical
teaching began to change. Recitation of works
by Hippocrates and Galen was replaced by
description of clinical cases and
semiological ideas, spread through the
invention of printing. L'Universa Medicina by
Jean Fernel (1497-1558) is an example. Fernel
was the first to describe yawning as a
prodrome of febrile states, calling it
"ephemeral fever". Still influenced by the
theory of humours, he described yawning as
helping "to evacuate harmful vapours". In a
similar vein, Jodocus Lommius published a
collection of observations in 1560,
Medicinalium observationum libri tres,
printed in Anvers by Plantin. Translated into
all European languages, this book gave rise
to 30 editions over 250 years and can be
compared to the modern-day Merck Manual. It
describes yawning as a prodrome of fever.
In 1624, Philippe Hechstetteri proposed
a similar collection of annotated medical
observations: Rararum Observationum
Medicinalium. "Every day at four o'clock in
the afternoon, a 14-year-old girl who had not
yet started menstruating experienced very
frequent, very irritating yawning followed by
diverse morbific accidents." He seemed to be
the first, long before JM. Charcot, to
consider repeated yawning as a sign of
hysteria.
Scipion Dupleix, philosopher and
historiographer of Henri IV and then Louis
XIII, published a wonderful collection in
1626: La curiosité naturelle
rédigée en questions selon
l'ordre alphabétique (Natural
curiosity compiled into an alphabetical list
of questions). Not without evoking Les Propos
d'Alain (by French philosopher Emile
Chartier), on the word yawn he submits to his
curious reader the following discussion, so
well phrased and close to our contemporary
ideas. "Why do we yawn when seeing others
yawn? This is due to the common disposition
of spirits or inside air, creating between us
all considerable sympathy, consent &
affinity, which moves and affects these
spirits alike by recollection only. And for
this same reason we cannot help singing when
we hear others sing, our attention being
otherwise occupied."
The 17th Century and
the Birth of Research
The first half of the 17th century was
marked by the birth of mathematical physics,
creating a new vision of the world. A new
scientific spirit was born with Descartes,
resulting in the mechanistic paradigm in the
field of physiology. After Galileo and
Newton, the discoveries in mechanics and
dynamics prepared the way for the concept of
"Man as Machine". Until this period, medical
dogmatism led to a major error: an
indifference towards research, as if medical
knowledge were fixed and confined. After
Harvey demonstrated blood circulation, the
experimental approach opened the way to the
quantitative analysis of vital phenomena,
owed in particular to Santorio.
Santorio Santorio (1561-1636), called
Sanctorius of Padua, a physician in Venice,
student and friend of Galileo, may be
considered as one of the founders of
experimental physiology. He tried to quantify
physiological and pathological phenomena with
measuring devices such as the scale, the
thermometer and the metronome. With a scale
of his own invention, he measured and
compared weight gain and loss in humans,
particularly by perspiration. He built an
entire medical theory based on the weight
differences related to nutrition, releases
via the emunctories and perspiration, calling
it static medicine. He mentioned yawning in
his aphorisms: "Yawning and limb extension
after sleep show that the body perspires
abundantly, similar to the rooster that flaps
its wings before it starts to sing. The urge
to yawn and stretch the limbs upon waking
stems from the abundance of perspirable
matter, creating an inclination to perspire.
Through yawning and limb extension we
perspire more in one half hour than we would
during other times in three hours."
In 1664, René Descartes
(1596-1650) exposed his theory on nerves in
his Traité de L'Homme (Treatise of
Man): "The spirits that are in the brain
enter into specific nerves; at the same time
they carry the strength to move a specific
limb. Having discussed respiration and other
simple and ordinary movements of this type, I
will explain how exterior objects act on the
sensory organs." Further on he explains
respiration through the muscular activity of
the diaphragm and focuses on "how this
machine swallows the meat at the back of its
mouth…". He concludes his complex
explanation of aerodigestive tract
functioning with the following: "By way of
example, you can also observe how this
machine can sneeze, yawn, cough, and make the
necessary movements to discharge a variety of
other excrements." This demonstrates that
nearly 1000 years after Hippocrates, the
evacuation of humours was still considered a
primordial effect of yawning.
Danieli Sennerti (1572-1637) also
continued to assimilate sneezing and yawning
as a mechanism of "morbific exhalation",
while pointing out the coincidence with
fatigue and somnolence, which had never
before been noted.
Jan Baptiste van Helmont (1577-1644)
was the first to challenge Hippocrates' ideas
in Des principes de médecine et de
physique pour la guérison des maladies
(Principles of medicine and physics for
healing diseases) in 1671. "Galen states that
the yawning usually accompanying the onset of
intermittent fever is caused by sooty vapours
that swell & distend the muscles of the
jaw, from which they try to detach
themselves. Why are these parts of the body
more excited than other parts by expulsion of
this sooty matter, given that the sooty
matter can only be the imperceptible
excrements of the most recent digestion? And
why is this matter encountered more during
fever than during gout, apoplexy, &c? Why
do we yawn in spite of ourselves when someone
else yawns? This demonstrates that yawning
does not proceed from sooty vapours, but from
the imagination. The School of Medicine does
not contest that the orifice of the stomach
is easily moved & excited to nausea by
disdain for something perceived or imagined
to be dirty, & that when some people
watch others eat sour apples, their mouths
immediately fill with saliva. Thus the upper
orifice of the stomach is easily moved by the
imagination, and sleep, Coma, Catoche,
catalepsy, drowsiness, vertigo & other
accidents of this type come from the orifice
of the stomach. Yawning which follows or
prefigures sleep is consequently attributed
to the same part of the body, because
phantasy resides there & it is not
without reason that we call this place the
heart. It follows that when we are noticeably
afflicted, we sigh repeatedly which seems to
relieve this upper orifice of its oppression.
When the lethargic & nonchalant stomach
makes us drowsy, taking the trouble to yawn
does not give any release to the muscles of
the mouth & trachea which are thereby
engaged. Similarly, the ethmoid bone,
disturbing the organ of smell, calls on the
muscles of the chest for sternutation. This
does not mean that the cause of yawning
should be sought in the muscles that move
when one yawns, no more than the cause of
sneezing should be sought in the muscles that
move when one sneezes."
Calling
Hippocratic Theories into
Question
Herman Boerhaave (1668-1738) is
considered the founder of clinical medicine
and the modern academic hospital. In 1680, in
Praelectiones academicae, he provided the
first novel explanation of yawning: "Yawning
and pandiculation favour the equitable
distribution of spiritus in all the muscles
and unblock the vessels of which sleep may
have slowed the functions. In certain cases,
yawning and pandiculation favour blood flow
and re-establish the nervous influx; their
action fights the excessive predominance of
the flexor muscles and returns everything to
its place." [...] "Yawning involves
extending most of the muscles controlled by
the will at almost the same time, while
expanding the lungs amply and inhaling a
great deal of air slowly & gradually.
After the air has been held for some time
& is rarefied, it is imperceptibly
released by exhalation & the muscles
finally return to their natural state. The
effect of yawning is thus to move all the
humours of the body through all the vessels,
to accelerate their movement, to distribute
them equally & as a result, to give the
sensory organs & muscles of the body the
capacity to perform their functions." The
dissertations of Johann Beutler (1685) and
Gottlob Hermann (1720) build on these
theories, adding a prognostic role to
yawning, considered to indicate a fever's
seriousness.
Pierre Brisseau associated yawning and
epilepsy for the first time in his
Traité des mouvements simpatiques
(Treatise on sympathetic movements) in 1692:
"The signs of an imminent attack of epilepsy
are a disturbance of the soul & the
senses, heaviness & pain in the head,
vertigo, irritating insomnia, weariness in
the joints, trembling of the limbs, ringing
in the ears, yawning, heart palpitation,
difficulty breathing, nausea, cardialgia,
&c. All of these signs are more or less
present in Epileptics. [...] Because
blood circulates with difficulty around the
lungs, yawning is easy to deduce in those
about to be struck by a fit of
Epilepsy."
In 1733, George Cheyne (1671-1743)
wrote The English Malady or a treatise of
nervous diseases of all kinds, in which he
explains: "Yawning & pandiculation seem
to be produced by hard concretions, by saline
particles, by harmful vapours, bitter or
acrimonious, by perspiration, by winds,
&c, that are either in or stop in small
vessels, or are carried to a part of the body
with many nerves such as the alimentary
canal, the cavities of the brain, the spine
or the interstices of the muscles. Because
the nerves in these places or their membranes
are irritated, a general disturbance takes
place in all nervous or sensible fibre, soon
producing the same effect throughout the
entire muscular system." [...]
"Vapours, or splenic disorder, are commonly
understood to refer to an excess of
dejection, discouragement, bloating of the
stomach, belching, noise in the lower
abdomen, ringing or buzzing in the ears,
yawning, lack of appetite, agitation, worry,
anxiety, ill humour, melancholy, sadness,
inconstancy, insomnia or drowsiness, or in a
word all the symptoms that do not form a
particular disease; but the vapours are very
often symptomatic & depend on another
malady." The premises of JM. Charcot's
"hystero-epilepsy" can be found here, and it
was not until the 20th century that epilepsy,
the cortical pathology, and hysteria, the
psychological condition, were separated.
Johannes de Gorter (1689-1762), a
prolific Dutch author in all areas of
medicine in the early 18th century, holds a
key place in the history of knowledge on
yawning. In his book De Perspiratione
insensibili in 1755, he attributed yawning
"to a need for faster blood circulation and
to cerebral anaemia". This marks the birth of
an idea that would persist for two centuries,
repeated by almost all authors: yawning
improves brain oxygenation.
Albrecht von Haller (1708-1777), a
Swiss physician and poet, wrote the first
compendium of human physiology (Elementa
physiologiae corporis humani: 8 volumes
published from 1757 to 1766). Following on
from Francis Glisson, he introduced the
notion of "irritability", the property of
tissues to be stimulated. He was the first to
record proof of this phenomenon and
distinguished nerve impulses (sensitivity)
from muscular contraction (irritability): "A
kind of harmony exists between the pulse
& the breath. In the natural state, there
are usually three or four pulsations during
one breath. If more blood reaches the heart,
the number of pulsations & breaths
increases. This explains why it is harder to
breathe when the body is in motion, because
the venous blood is whipped &
accelerated. If there is greater distance in
the lungs, & the blood has trouble
passing from the right to the left ventricle,
the number and length of breaths will be
greater in order to cover the distance. This
is the cause of sighs and yawning." He goes
on to describe sleep: "As night approaches,
one feels a numbness in the long muscles
& their tendons, together with an
incapacity for serious thought & a love
of rest. At this point, the forces holding up
the body weaken, the eyes close, the lower
jaw is left hanging, which forces one to
yawn." In the same vein as de Gorter, he
advances the following: "Why do we yawn when
we feel like sleeping? In order to clear the
lungs in which the blood is moving more
slowly."
David Hartley (1705-1757), an English
physician influenced by the discoveries of
Isaac Newton, attempted to explain human
physiology using physical laws based on the
laws of gravity. Like Hippocrates who
transposed Aristotle's knowledge of Nature
into four humours, Hartley proposed that
perceived sensations and voluntary acts were
dependent on the vibration of particles that
composed human tissue and were invisible to
the eye, travelling the length of the nerves
and thereby giving substance to the "animal
spirits" of Descartes. He therefore
prefigured the concept of molecules:
"Depending on the circumstances, yawning and
stretching may be considered part of the five
classes of vibratory movements. When yawning
occurs during attacks of fever & other
diseases, it appears caused by sudden, strong
contractions in the membranes of the mouth,
throat, trachea & oesophagus, whereas
stretching appears caused by skin
contractions."
Surprisingly, very few authors have
evoked yawning in animals or children.
Charles Porée (1685-1770) spoke about
yawning during a public session of the
Académie des Belles-Lettres de Caen in
1756 where he observed, "Birds yawn, just as
man & several other animals do, but their
yawning is different from ours. The lower
part of the bird's beak is stable, whereas
the upper part is mobile through a hinge
connecting the bones of the bird's head to
its beak. Our upper jaw is fixed, the lower
jaw is mobile & moves with the temporal
bones. When man yawns, the lower part of the
mouth opens; while the mechanism differs,
nature's intention is the same & reaches
the same objective. The rest of this
observation has mere curiosity value. We yawn
when we are born; the first infant to be born
set the example. This movement cannot be
attributed to worry, as the infant knows the
society he enters. Hunger & sleepiness
are not the immediate cause; food will be
administered through a new channel. So at
first yawning has to be related to the change
the infant experiences as he begins to
breathe and thereafter, to the new course the
blood works its way through. It can also be
seen as a sign of weariness caused by the
fatigue of birth and the new oscillation of
the humours. All these changes are admirable
and show a providence worthy of our deepest
esteem. Nonetheless, one could complain that
birth as well as death are difficult, &
life is often less tiresome."
Joseph Raulin (1708-1784) tried to
classify the nervous disorders of the ladies
he treated at the court of Louis XV. In his
Traité des affections vaporeuses du
sexe (Treatise on vaporous affections of the
female sex), he compared spasms and
convulsions and used the expression of the
period &endash; vapours &endash; to describe
what would later be known as hysteria,
characterised by Paul Briquet and Jean
Baptiste Louyer-Villermay at the beginning of
the 19th century: "A woman experiences
anxieties, yawning, hiccups, spasms and
irregular movements in her nerves, of which
she complains bitterly; her family, friends
and neighbours respond with indifference.
This is a case of vapours. These light
vapours progress imperceptibly, the patient
becomes sad, she sheds tears, or she seems
cheerful, she uses expressions that are not
understood, or she says pretty things, she
laughs, she sings, or she alternates tears
& laughter, always being beside herself.
We laugh as she does, attributing this to the
vapours."
History does not remember the name of
Jean-Férapie Dufieu. Yet he wrote a
treatise of physiology for students,
published in Lyon in 1763, in which he
compiled the knowledge of his times in a
literary style long forgotten in our modern
manuals: "When we wake, we yawn, stretch our
arms, we are more agile, our spirit is more
vivacious. Since the nervous juices do not
flow through the muscles during sleep, all
fibres are sluggish. Thus we have to contract
them all, to open the passage for the nervous
juices that have filtered into the brain, or
to bring them into these parts. In addition,
since the movement of blood through the
muscles is sluggish, its course has to be
hastened; this is done by contraction where
the muscles enter when the limbs are
stretched. Yawning has the same cause. These
nervous juices that enter into the muscles,
& that have gathered up in large
quantities, make us more agile, because the
soul can send a large amount into the nerves
to move the body parts." This colourful
description is close to many of our current
concepts at the start of the 21st century!
In 1767, Achille Le Vacher de la
Feutrie compiled a dictionary of surgery, in
which he returned to the concepts of
Sanctorius and de Gorter: "Imperceptibly we
render a large quantity of perspirable matter
when nature causes yawning and limb
extension. We are more prone to yawning
immediately after sleep than at other times,
because a larger quantity of this perspirable
matter escapes through the pores of the skin
than at other times. The increase in
contraction following this affluence causes
the retention of perspirable matter in the
passages of the skin; & that is the
reason for the irritations that precede
yawning & limb extension. During those
movements all membranes of the body are
shaken, their fibres are spread & the
retained matter can escape."
Following Sydenham in England,
François Boissier de Sauvages
(1706-1767), a famous practitioner at the
University of Montpellier, tried to classify
diseases using a methodology inspired by
Linnaeus in the natural sciences, who
generated great interest in taxonomy during
that time. Boissier published a large body of
work on all subject matters, but his
Nosologie Méthodique ou distribution
des maladies en classes, en genres et en
espèces (Methodical nosology or
assignment of diseases to classes, types and
species) remained his most famous work:
"Through the full & deep breathing that
accompanies yawning, all pulmonary vesicles
dilate, blood circulation in the lungs
accelerates, the viscera of the lower abdomen
compress, the eyes water, saliva flows
abundantly, the hearing muffles, a sort of
buzzing is felt inside the head, the
Eustachian tube dilates, talking is
impossible, perspiration increases, the soul
experiences a sort of exquisite pleasure, and
the person becomes more energised and more
alert." Boissier goes on to review different
kinds of pathological yawning: during
haemorrhages as during fevers yawning
announces a fatal outcome, whereas "stomach
yawning" bears witness to indigestion and
disgust. He also describes vapours
accompanied by yawning, which he qualifies as
hysterical.
Samuel Tissot (1728-1797) returned to
practice in Lausanne after having studied in
Montpellier. As a physician to prominent
figures between 1750 and 1797, he was
consulted all over Europe, often by
correspondence. His archives contained all
the medical correspondence, including
prescriptions, that he conducted with his
patients. His Avis au peuple sur sa
santé (Notice to the general public
concerning their health) was a true early-day
bestseller, translated into twelve languages
and published in 17 editions. It was the
first medical book written for the general
public in the vernacular language. But above
all, Tissot is the author of the first
treatise on neurology, Traité des
nerfs et de leurs maladies (Treatise on
nerves and nervous disorders, 1768-1770), the
first volume of which is entitled
Traité de l'épilepsie (Treatise
on epilepsy). He attributed the transmission
of information from one body part to another
to a fluid circulating in the nerves that he
called "sympathies": [...] "Such is
the admirable constitution of man and animal,
that those parts with seemingly different
functions are however intertwined such that
they all more or less influence one another
[…] But aside from this general
harmony, there are different parts that have
a more direct connection, that are linked by
different means, such that the state of one
has a pronounced influence on the state of
another, or is at least altered by the
changes that it experiences; this is due to
the Greek sympathia & the Latin
consensus; & sometimes the effect is much
more pronounced on the part in sympathy than
on the part originally affected."
[...] "Since specific sympathies
depend on nerves that have closer
connections, weak causes can set them into
motion; stronger causes are needed to bring
about the well pronounced effects of general
sympathy. All men are not equally subject to
sympathies, because the nervous nature is not
equally sensitive in all; hence, the same
cause that brings about the most pronounced
sympathies in one person, causes none in
another; the corresponding action is limited
to its centre, because the nerves of that
person are less sensitive. It is strictly to
the general consensus that we must attribute
this imitative force that obliged Monro to
repeat all that he saw being done. M. Whytt
attributes yawning and involuntary vomiting
to it; but I nonetheless do not know whether
simple physical consensus is capable of
generating these phenomena by itself."
Robert Whytt (1714-1766), a medical
professor in Edinburgh, is known for having
described tubercular meningitis. His
explanation of "sensations" (sensitivity) in
involuntary movements makes him a forerunner
in the area of reflexes, just as his interest
in the effect of emotions during diseases
makes him the father of psychosomatic
pathology: "The different parts of our body
receive from nerves not only the power to
feel & move, but also a very specific
sympathy that is either general & spreads
out over the entire animal system, or
particular, meaning that it is mainly exerted
between certain parts. Whether we want to or
not, we close both our eyelids every time
there is a threat to one of our eyes. A
sudden bright light striking our eyes
sometimes causes blindness. Hippocrates
observed that the sudden sight of a snake can
make the face go pale. When a hungry person
sees food he likes, he experiences a more
abundant secretion of saliva than before
having seen the object. Yawning &
vomiting often occur by the simple sight or
sound of someone yawning or vomiting. In this
work on nervous disorders, I will mainly
examine those that have the effect of a weak,
delicate & unusual nervous constitution;
& in this category I place the majority
of symptoms that physicians have commonly
described as windy, spastic, hypochondriacal,
hysterical and vaporous. [....] Those
that can suddenly be felt in the entire body
or that travel through it; shivers; a feeling
of coldness in certain parts as if water were
being poured on them; at other times, an
unusual feeling of fire […]
Heart palpitations, rapidly changing pulse,
most often natural, sometimes unusually slow,
& other times quick or frequent, more
often faint that strong, & in certain
cases irregular or intermittent
[…] A dry cough with breathing
troubles, or a convulsion or tightening of
the bronchi, an accident that may come back
periodically, yawning, hiccups, frequent
sighing, a feeling of suffocation or
constriction that seems to be caused by a
lump or large object lodged in the throat,
fits of crying & convulsive
laughter."
Erasmus Darwin (1731-1802) is famous
for being the grandfather of Charles and the
author of Zoonomia, or The Laws of Organic
Life (1794). In this work, he is the first to
describe the movement of a paralysed arm in a
hemiplegic during yawning: These involuntary
motions are often seen in paralytic limbs,
which are at the same time completely
disobedient to the will."
L'art de connaître les hommes par
la physionomie (The art of understanding men
by their physiognomy, 1775-1778) by Gaspard
Lavater (1741-1800) was the result of a
philosophical movement dating back to
Antiquity that consisted of deciphering an
individual's personality from his facial
features. Lavater's chapter on yawning was
particularly novel: "During the most
passionate moments, the jaw often has an
involuntary movement just as during moments
when the soul is unaffected; pain, pleasure
and boredom also cause yawning, but it is
true that vivid yawning is a convulsion that
is very prompt during pain or pleasure,
whereas the yawning of boredom shows its
character by the slow pace at which it
occurs."
19th Century: Yawning
and Hysteria.
François Magendie (1783-1855)
demonstrated the discoveries of Charles Bell,
who distinguished the ventral roots as being
motor nerves and the dorsal roots as being
sensory nerves. Magendie defended his thesis
on 27 March 1808: Essai sur l'usage du voile
du palais (Essay on the use of the soft
palate) which included a novel chapter on
yawning: "Yawning, classified by
physiologists among inhalation phenomena, has
not been sufficiently studied in my opinion.
It is generally considered a long inhalation
made necessary by the slowing of the
circulation upon waking, before sleep and in
melancholy passions such as boredom, etc. But
if we attentively examine yawning, we
recognise that it is often composed of
several inhalations and exhalations. At other
times it occurs after inhalation, thus during
exhalation. In certain rare cases we yawn
without breathing in or out; this strongly
suggests that yawning mainly consists in the
pandiculation of the masseter, temporal and
pterygoid muscles and in the prolonged
contraction of the submandibular muscles. I
do not completely exclude the purpose given
by physiologists to yawning, but I think it
must be seen as accessory. Another reason
makes me persist in this idea: yawning is
almost always accompanied by the
pandiculation of other muscles in the body,
and important muscles such as the masseter
and pterygoid muscles must necessarily take
part in the well-being resulting from this
elongation. Do we not observe in the jaw
muscles the two kinds of pandiculation seen
in the trunk and the limbs? In one, the most
frequent kind, we extend the limbs, we arch
the trunk backwards, the flexors are
elongated, the extensors contracted. In the
other, the opposite happens, meaning that the
trunk and the limbs are in the greatest
degree of flexion possible: the extensors are
elongated, the flexors are strongly
contracted. We find these two kinds of
pandiculation in the muscles of the lower jaw
during simple yawning: the levators are
elongated, the depressors contracted; in a
particular state that has not yet been
described, the levator muscles as well as all
facial muscles enter into a violent
contraction and we experience a sensation
that is perfectly identical to the one felt
during yawning."
Julien César Legallois (1770-1814)
was a pioneer in experimental physiology. In
1813 he published his Expériences sur
les principes de la vie (Experiments on the
principles of life) in which he described
sectioning the spinal cord of live rabbits in
several locations, which allowed him to place
the respiratory centres in the brainstem. He
reported the occurrence of yawning numerous
times and considered it as a ventilatory
movement: "Whatever the origin of respiratory
nerves, the motive force for the respiratory
function is undoubtedly in the brain. Were
new proof needed, the yawning I observed
after sectioning the spinal cord provides us
with evidence that appears irrefutable."
"Yawning clearly depends on the same
motive force as spontaneous inhalation;
yawning is the remains, and to some extent
the vestiges of this inhalation."
Auguste Landre-Beauvais (1772-1840)
created a new genre by proposing one of the
first books on medical semiology:
Traité des signes des maladies
(Treatise on the signs of diseases, 1815). He
described yawning associated with diverse
pathological states: "Yawning generally
occurs before febrile shivering. It sometimes
occurs in ataxic fevers and frequently
precedes eruptions and haemorrhages. Attacks
of gout, hysteria or hypochondria are often
presaged by continuous yawning. Frequent
yawning is sometimes observed during early
pregnancy. Yawning is a phenomenon that
occurs after serious injuries, excessive
evacuation and internal inflammations; when
accompanied by serious symptoms, it is a very
worrisome sign. Frequent yawning during
ataxic fevers may be considered very
dangerous, particularly in connection with
other phenomena that precede weakness. The
same is true for yellow fever, the plague,
and phlegmasia complicated by ataxic fever.
Frequent yawning sometimes occurs in women
during childbirth, indicating that the
delivery will be difficult and that the
mother's strength is oppressed or weakened. A
feeling of weariness and heaviness in the
limbs and less lively sensations immediately
precede yawning. It is followed by increased
cheerfulness and vivacity. The pulse becomes
quicker and the temperature often increases.
The secretion of tears and saliva is more
abundant. If we relate these phenomena to
what preceded the yawning &endash; fatigue,
boredom, an exterior cold &endash; it seems
that the objective of this effort is to
improve the circulation in the lungs where
the air flow has encountered obstacles
produced by either spasm or plethora."
The first medical encyclopaedic
dictionary of the 19th century was written by
Charles-Louis-Fleury Panckoucke (1780-1844)
and published in 60 volumes from 1812 to
1822. He solicited the great medical minds of
his time such as Alibert, Pinel, Esquirol,
Laënnec, Desgenettes and Larrey. This
dictionary, including more than 4000
bibliographic records and just over 200
illustrations, was an attempt to summarise
the medical knowledge of the time, at the
dawn of clinical medicine and anatomical
pathology. The dictionary was a large
commercial success, a source of wealth for
its sponsor and a far-reaching vehicle for
French medical thinking. The entry on yawning
was novel because it evoked yawning in
animals and described fetal yawning, never
before reported: "The Latin term for yawning
comes from oscitatio; in French,
bâillement is derived from the Latin
balare, to bleat. Yawning consists of a large
inhalation occurring slowly, and in general
with wide opening of the jaws, followed by a
prolonged exhalation, often accompanied by a
muted noise. It is generally thought to be
caused by a problem with pulmonary
circulation. This opinion, while not being
backed by any positive fact, does appear
likely: almost all causes of yawning coincide
with a certain weakness of the entire system,
which could very well produce the problem we
are discussing; the causes are boredom,
sleepiness, fatigue, hunger, and the malaise
preceding intermittent fevers, etc. Animals
put into the pneumatic machine, those that
are placed in non-breathable air, yawn
several times before dying. A fetus taken
alive from its mother's womb by caesarean
operation yawns as well. Finally, it seems
that damage to the pulmonary tissue can cause
frequent yawning. In many cases this
phenomenon seems related to the state of the
stomach rather than to state of the lungs,
which are only affected sympathetically; in
this way, difficult digestion or a simple
stomach pain, whatever the cause, is
accompanied by repeated yawning. This
incident can also be purely spasmodic, as
observed in women affected by hysteria, or in
individuals with convulsive diseases. Yawning
is, to a certain extent, an involuntary act.
We can overcome the action of muscles
tightening to lower the jaw by contracting
their antagonists; we can moderate the
exhalation that ends yawning and prevent its
accompanying noise. But the long inhalation
that constitutes yawning itself cannot be
suppressed, undoubtedly because the agent of
this inhalation, the diaphragm, receives part
of its nerves from the system of ganglia, as
M. Roux has noted. Bichat suspected that the
object of this involuntary act is to renew
the air contained in the lungs more
completely than can be achieved by ordinary
inhalation, and thus give way to greater
absorption of oxygen."
François-Joseph Double
(1776-1842), famous during his time and a
founding member of the Académie de
Médecine, also published a treatise on
semiology and disease in 1817:
Séméiologie
générale ou traité des
signes et de leur valeur dans les maladies.
In his work he summarised the same findings
as Landre-Beauvais: "A rapid consideration of
the mechanism of yawning clearly suggests its
degree of influence on the system. Its
importance cannot be denied if we think about
the general state that precedes and follows
it, for example, the kind of stupor and
torpor that prepares the way and the
weariness and weakness we feel beforehand, in
contrast to the pleasant sensation that
follows and the relaxation and well-being it
procures. By reflecting on these diverse
subjects, we find the indication for most of
the signs that experience has attached to
yawning […] Pandiculation
consists of successive stretching of all
muscles accompanied by a pleasant sensation
and generally followed by yawning.
[...] Pandiculation is a very
positive sign leading into convalescence, but
if it continues and persists relentlessly, it
indicates a deterioration. During the course
of a disease, pandiculation is always
salutary; it signals the favourable state of
the vital forces and the resistance with
which nature fights the effect of the
disease."
During the same period, at the age of
22, Anthelme Richerand (1779-1840), known for
his quarrels with Dupuytren, published
Nouveaux éléments de
physiologie (New elements of physiology).
This important compilation of writings from
the period lacked originality but possessed a
style that made it a highly successful
teaching tool, as this account confirms:
"This work brought charm and beauty to our
school years. It was a delightful
introduction to the austere study of
Medicine; the reading could be considered
light, but it seemed to sprinkle the
subject's first paths with flowers." The
article on yawning demonstrates this: "We
also yawn upon waking, in order to lift the
thorax muscles to an appropriate degree for
respiration, which is always slower, less
frequent and deeper during sleep than during
the waking state. Due to a similar need,
waking in all animals is marked by
pandiculation, a muscular action in which the
muscles seem to accommodate the contractions
that the movements dictate. The crowing of
the cock and the agitation of its wings serve
the same purpose. Finally, the same necessity
leads the numerous flocks of birds that
inhabit our woods to warble endlessly at
sunrise and fill the air with harmonious
song, in which the poet hears the joyous hymn
by which the feathered populace celebrates
the return of the god of light!"
Nicolas Adelon (1782-1862) was the
author of a long article devoted to yawning
in the Dictionnaire de Médecine
published in 1821. He expanded on the
respiratory theory of yawning, helping to
ensure its 150 years of success: "In the
state of health, yawning occurs in a vacuum,
in a situation where there is no renewal of
fresh air, because in these cases there is
not enough air, or the air contains less
oxygen, and we try to compensate by
introducing a large amount of air to where it
is lacking. This is why yawning is a
precursory phenomenon of all gradual
asphyxiations. We yawn when sleep approaches,
because the momentary paralysis that seizes
all muscles in the body also seems to seize
the respiratory muscles, which results in a
temporary decrease in the frequency of
inhalation. Since the circulation has
continued in the meantime, and as a result
has carried the same quantity of venous blood
to the lungs to be transformed into arterial
blood, there is not enough air to perform
this conversion, and a small amount of venous
blood remains in the lungs, slightly blocking
pulmonary circulation: yawning thus occurs
automatically to introduce a larger quantity
of air, the quantity needed to arterialise
the leftover venous blood and restore
balance. Yawning occurs in all circumstances
where we see this accumulation of venous
blood in the lungs, this blockage of
pulmonary circulation. It is thus considered
a physiological remedy for dissipating this
engorgement, and its full accomplishment is
followed by a sensation of well-being.
Judging from this feeling, the outside air
introduced into the lungs by yawning could be
considered to overcome the obstacle blocking
the circulation in these organs. We also yawn
during the first moments of waking, because
inhalation occurs in a different mode than
during sleep, and in the passage from one
mode to the other, there is a momentary
decrease in inhalation, due to an imbalance
in the amount of air introduced and the
quantity of venous blood to be transformed
into arterial blood. The result is a slight
pulmonary engorgement, leading to the
phenomenon necessary clear it."
During the same period, John M. Good
(1764-1827) explained yawning and
pandiculation in The Study of Medicine with a
Physiological System of Nosology in England.
Taking a very different approach from his
contemporaries on the continent, he never
evoked the ventilatory mechanism, but saw
yawning as simple muscular work necessary for
the balance between extensors and flexors.
These notions come close to modern-day
physiological observations.
In 1861, Adolphe Dureau de la Malle
(1777-1851) published a dissertation on the
development of intellectual faculties in wild
and domesticated animals in the Annales de
Sciences Naturelles. He reported having such
close ties to his dog that the latter started
yawning when he saw his master yawn! A
current-day author, A. Senju, published a
study in 2008 that comes to similar
conclusions.
François Broussais (1772-1838)
broke away entirely from his contemporaries
and predecessors in his Traité de
physiologie appliqué à la
pathologie (Treatise on physiology applied to
pathology), published in 1834: "If we wish to
study the mechanism of yawning, which can be
considered as the first sign and main
phenomenon of boredom, either moral or
physical, we will encounter serious problems.
Yawning has been related to the need to
breathe, or considered a means to renew the
air stagnating in the lungs after respiration
has slowed for some time. This is an error
&endash; one must only be a practitioner to
know with certainty that dyspnoea alone never
produces yawning." [...] "The lungs
seem to be much less influenced by yawning
than the stomach" [...] "[I]f
the need for air is not the principal cause
of this deep aspiration, then what can its
purpose be? Could it be to swallow air, and
to cure an ill stomach?" This novel approach
did not generate much response and the
ventilatory theory persisted.
John Abercrombie (1780-1844), a
Scottish physician, published Pathological
and practical researches on the diseases of
the brain and spinal cord in 1828, which was
translated into French in 1832. He described
the strange phenomenon encountered in certain
hemiplegics where the paralysed arm moves up
towards the mouth simultaneous to yawning.
This occurrence disappeared as soon as the
paralysis subsided.
1n 1842, Pierre-Marie Flourens
(1794-1867) gave a clear explanation of motor
automatisms and their coordination
(Recherches expérimentales sur les
propriétés et les fonctions du
système nerveux dans les animaux
vertébrés, [Experimental
research on nervous system functioning in
vertebrates]): "The spinal cord is
restricted to linking muscular contractions,
the first elements of all movement, into
complex movements. Although the spinal cord
is the point of departure for almost all
nerves determining these contractions and
movements, it is not the seat of the
admirable power to coordinate them into
specific movements: jumping, flying, walking,
running, resting, etc.; or inhaling,
shouting, yawning, etc. This power resides in
the cerebellum for the first group, in the
spinal bulb for the second group. There is
one last consideration to note. The movements
of respiration, shouting, yawning, etc., are
commonly called involuntary, whereas
locomotive movements are called voluntary."
Louis Delasiauve (1804-1893) and
Théodore Herpin (1799-1865) are
associated with the detailed description of
the different types of epilepsy, which
include generalised and partial seizures.
They described prodromes warning the patient
of an imminent seizure, notably repeated
yawning. These symptoms are currently
attributed to partial temporal seizures.
End of the 19th Century: Is Yawning a
Reflex?
Jean-Louis Brachet (1789-1858), an
eminent physiologist in Lyon, was the first
to contest the respiratory role of yawning:
"Yawning is generally defined as a large,
deep inhalation occurring slowly that moves
the lower jaw, the hyoid bone and the larynx
considerably downward. It is followed by a
prolonged exhalation accompanied by a
particular muted noise. Yawning is attributed
to the need to renew air in the lungs, or to
introduce a larger quantity of air to supply
the blood with more oxygen, because the flow
is blocked and oxygen is consequently
lacking. Or yawning is attributed to a
feeling of malaise arising in the back of the
throat, in the upper part of the neck. We do
not share this view. We do not consider the
phenomenon to be limited to this convulsive
contraction of the facial and neck muscles,
nor to this larger volume of air that it
sends through the airways. Yawning is not a
purely local phenomenon pertaining
exclusively to respiration: it is a general
phenomenon pertaining to the complete system"
[...] "We therefore think yawning, as
well as pandiculation, occurs when the brain,
alerted by the torpor seizing the system,
tries to prevent the consequences by
soliciting acts of excitation and arousal;
thus all muscles contract, the locomotive as
well as the respiratory muscles. This general
contraction is already a means of
stimulation."
Almire Lepelletier de la Sarthe
(1790-1880), a proponent of physiognomy which
Johann-Casper Lavater developed in 1775,
largely surpassed his master with his
reprehensible words: "When yawning is
customary, we can assume the following about
the subject: limited intelligence, without
initiative, slow and lazy mind, inactive,
soft character, weak, indolent, timid,
indifferent, melancholic, boring, incapable
of vigorous resolution or undertaking a long,
difficult or perilous enterprise, at times
clever and cunning, and given to
contemplating theft and fraud in his
dealings."
In 1865, Jules-Bernard Luys (1828-1897)
published Recherches sur le système
nerveux cérébro-spinal, sa
structure, ses fonctions et ses maladies
(Studies on the cerebrospinal nervous system,
its structure, functions and diseases). He
described the central grey nuclei, giving his
name to one of them, and postulated on their
physiological role, which had never been
studied before his time. He developed novel
ideas concerning yawning as well: "Although
not extensively discussed, it is a common
observation that when the brain cells start
to become inactive, the medullary regions of
the spinal axis with immediate control over
the respiratory apparatus are altered in
their functioning. Everyone knows that
yawning is a premonitory sign that the
conditions of diurnal functional activity in
the nervous system have ceased to be what
they previously were. What is yawning if not
an involuntary inhalation indicating that the
innervation of automatic activity acquires a
predominate influence in the medullary
region, following retrocession of the
cerebral influx, and that at this precise
point of the spinal axis, a sort of
interregnum occurs and a disturbance of the
original stimulus. In addition, the highly
characteristic rhythm of the respiratory
movements during the period of brain
collapse, their well-measured succession and
their overtly automatic nature lead us to
believe that they are no longer controlled by
the same centres of innervation that supply
them during the waking state."
We have now reached the end of the 19th
century, which was dominated by the work of
Jean-Martin Charcot (1825-1893) and his
students Charles Féré
(1852-1907) and Georges Gilles de la Tourette
(1857-1904). The most famous observation of
pathological yawning was presented by JM.
Charcot on Tuesday, 23 October 1888. His
young 17 year-old patient yawned 8 times per
minute, or 480 times per hour, only
interrupted by sleep; she had generalised
epileptic seizures, complete anosmia and
binasal hemianopsia. Reporting this
observation in the La Nouvelle Iconographie
de la Salpêtrière in 1890,
Gilles de la Tourette specified that she had
been amenorrhoeic for nearly a year, but he
did not indicate whether she was examined for
galactorrhoea. And yet JM. Charcot noted:
"After what I have told you, you have
undoubtedly surmised that we are in the
domain of hysteria." If we may criticise the
master 120 years later, JM. Charcot's young
patient was most likely suffering from a
prolactinoma compressing her optic chiasma
and her hypothalamus. Surprisingly, JM.
Charcot continues his discussion without
evoking any criticism: "Physiologically we
affirm that this is an automatic act,
required by a certain degree of anoxemia, a
need for oxygenation of the nervous centres."
In the third volume of La Nouvelle
Iconographie de la Salpêtrière
(1890), Gilles de la Tourette added four
other observations involving abnormal
movements and convulsions attributed to
hysteria. It is difficult to establish an
exact diagnosis, but an organic pathology
involving the thalamus or hypothalamus seems
probable, such as a tumour with intracranial
hypertension or a chronic tic disorder. In
1895, Gilles de la Tourette reviewed and
commented on these cases again in his
Traité de l'hystérie en trois
volumes (Treatise of hysteria in three
volumes), justifying what he believed to be
their hysterical origin. Lastly, in 1905,
Féré published a report on
yawning to the Société de
Biologie that describes his efforts to
measure muscular force, observing its
decrease after yawning.
Paolo Mantegazza (1831-1910) was an
Italian psychologist and author of La
physionomie et l'expression des sentiments
(Facial characteristics and the expression of
sentiment). He was the first to report:
"Yawning expresses a wide variety of things,
such as hunger, thirst and, especially in
women, the need for physical love; but in the
expression of pain it is a characteristic
element of boredom."
In 1891, Henrietta Russell, an American
from New York, published a book called
Yawning. In it, she described natural
gymnastics, comparable to contemporary
relaxation, and explained the benefits of
yawning, which results from relaxation and
produces a feeling of release and well-being.
She has since gained a following, and a
thesis was dedicated to this topic in 2006 in
France.
20th
Century
The year 1901 is key in the study of
yawning. René Trautmann (1875-1956)
defended his doctoral thesis &endash; Yawning
&endash; in Bordeaux under the direction of
Paul Vergely. It is the first of three
dissertations on this topic presented in
France during the 20th century, and by far
the most interesting. Trautmann, educated in
a military medical school, spent his entire
military career as a physician in Africa. He
produced ethnological studies that were
marked by the colonising spirit of the
period, in addition to a few short stories
based on his travels. His thesis presents a
very rich historical perspective and one that
is still very useful. Trautmann described the
activation of the facial muscles and
respiratory channels in detail, as none of
his predecessors had, and concluded that
yawning improves blood oxygenation. He
reviewed the different theories explaining
the contagiousness of yawning and proposed
that "yawning falls into the category of
occurrences reinforced by habit and favoured
by moral depression. When the mind
concentrates, when we are very attentively
listening to a story, we do not yawn, even if
one or more people engage in this act.
Yawning is a purely imitative phenomenon, as
are the gestures and involuntary facial
movements executed by many individuals
attending a speech or declamation. Depending
on the subject, more frequent yawning is the
result of a greater tendency towards
instinctive imitation." Trautmann accepted
the idea that yawning is involuntary but
challenged the historical writings he cited
by proposing a method to trigger yawning at
will: "[F]or some time we have
observed that we can wilfully effectuate
complete yawning by means of a particular
mechanism; several of our colleagues, who are
medical students, have reached the same
conclusion. One need only tighten the
subhyoid muscles vigorously while inhaling
slowly and profoundly. The lower jaw is
dropped down and pushed forward, and there is
a buzzing in the ears: yawning takes place."
Trautmann thoroughly reviewed all forms of
pathological yawning and added personal
observations of a rapid succession of yawns
during shivering at the onset of fever. A
long chapter describes yawning in pregnant
women, especially during puerperal fever or
delivery accompanied by haemorrhaging. It is
completed by Trautmann's own observations. In
his conclusion, he writes: "While yawning
always occurs in the same manner, it can be
considered &endash; as a muscular act and
depending on the case in which it occurs
&endash; as a particular type of reflex: a)
an exclusively spinal reflex, b) a
mesencephalic reflex or c) a cerebral and
cortical reflex." At the end of his thesis,
Trautmann challenges the ventilatory theory,
which does not explain all the clinical cases
he presents, and his work suggests the
existence of neurological mechanisms that
trigger yawning. Trautmann thus appears to be
the first modern-day thinker on yawning.
In 1905, André Vigouroux and
Paul Juquelier wrote a book entitled La
contagion mentale (Mental contagion). They
saw yawning as a reflex, which made it
contagious by nature. In particular, they
developed a hypothesis that became successful
under the term théorie de l'esprit
(mind theory). It stated that by
involuntarily mimicking the gestures, actions
and emotions of others, we acquire the
ability to decode the feelings of the person
we observe. Interest in this theory was
renewed with the discovery of mirror neurons
at the end of the 20th century.
"[T]he sight of coordinated, rhythmic
actions that have become reflexes for those
who perform them, provokes in onlookers motor
reactions that are perfectly involuntary but
also rhythmic and that represent a rough
reproduction of the perceived acts."
In 1916, FH. Pike from Columbia
University in New York proposed a
comprehensive review in the Journal of
Heredity. Taking account of animals and human
fetuses, Pike rethought the origin of
yawning, discussing both the influence of
hunger and the need to fight an enemy.
In the 21 January 1905 issue of The
Lancet, John Hughlings Jackson described a
personal observation. While performing a
funduscopy on a patient, he suddenly observed
a retinal paleness attributed to an
arteriolar spasm that was quickly followed by
yawning, which restored the appearance of the
retina.
The period following World War I was
marked by a significant epidemic of
encephalitis lethargica, also called von
Economo disease. In addition to the lethargic
forms that were often fatal, or the curable
forms that left the patient with Parkinson's
disease and abnormal movements (oculogyric
crises), a rarer form of encephalitis
manifested itself through stubborn and fatal
insomnia, very often accompanied by a rapid
succession of yawns. In 1921, Jean Sicard and
André Paraff published a case
associated with uncontrollable laughter,
comparable to gelastic epilepsy. In 1922,
Gabrielle Lévy, a student of Pierre
Marie and Jean Lhermitte dedicated her thesis
to this topic in France. At the same time,
MacDonald Critchley and Smith E. Jelliffe in
the USA, Raymond de Saussure in Switzerland,
and Georges Guillain and Pierre Mollaret in
Paris all collected observations in which
yawning can be interpreted as abnormal
movement, similar to tics and relaxation
behaviour at the end of involuntary episodes
of hyperventilation.
Edouard Claparède (1873-1940)
was a Genevan physician and psychologist. One
of his specialties was child psychology. In a
journal for teachers entitled L'Educateur, he
published an article in 1924 that drew on the
work of the German Valentin Dumpert (1921).
He noted that yawning results from a massive
contraction of the diaphragm and is part of
pandiculation, rather than being directly
tied to breathing. He was the first to
overturn the paradigm of ventilatory yawning,
pioneering today's neuromuscular theory in
which yawning has a diencephalic origin:
"Yawning is only incomprehensible when
considered alone. On the contrary, it becomes
clearer if we see it as part of a more
general reflex, the reflex of stretching. It
is well known that yawning hardly ever occurs
without general stretching of the body. This
is striking in certain animals, such as dogs
or cats. It is also evident in small infants,
and very often in adults." Through
self-observation, Dumpert noted that
voluntary stretching activates yawning. (This
is easy to reproduce.) He also observed that
yawning evokes associated movements in
hemiplegics; they present extension in their
paralysed limbs that lasts throughout the
yawn. Claparède was convinced that
these associated movements were part of the
stretching reflex. [...] "When one of
our listeners yawns, can we assume he is
tired of listening to us, when on the
contrary, he may be doing his best to keep
listening?" Yawning thus became a means of
stimulating vigilance, a true
revolution!
In 1937 Paul Delmas-Marsallet presented
an article entitled "Le signe du
bâillement dans les lésions du
cerveau frontal" (Yawning in frontal brain
damage) in the journal
Oto-Neuro-Ophtalmologie. He described five
observations of uncontrollable yawning
resulting from either frontal haematomas or
frontal tumours. He proposed that
uncontrollable yawning was a clinical sign of
intercranial hypertension, which remains
true.
In 1946 Paul Heusner published the
first summary article in English in
Physiological Review. Phylogenesis emerged
for the first time. Heusner precisely
described different durations and
scientifically measured daily timescales. He
proposed that the brainstem and basal ganglia
were responsible for yawning, based on
yawning in anencephalic newborns and in
hemiplegics during brachial parakinesis.
In 1958 Jean Barbizet published a large
compilation of data and historical
information in French and English, together
with the first radioscopic measurements,
which he had taken, of pharyngolaryngeal
expansion during yawning. He thus showed that
during the culmination of yawning,
pharyngolaryngeal diameter is multiplied by
four. He also described the first works of P.
Passouant, who triggered experimental yawning
in cats by electrostimulation of the
hypothalamus. In addition to mentioning
involuntary parakinesis in the paralysed arm
of a hemiplegic, he reported the unusual
observation of D. Furtado, in which passive
movement in the paralysed arm of a polio
patient triggered yawning, which has never
been reported since.
In 1962 A. Montagu wrote an article in
the JAMA that has since been frequently
quoted. He proposed that yawning stimulated
vigilance, while attributing lowered
vigilance to insufficient brain
oxygenation.
J. Boudouresque attempted to summarise
knowledge on yawning for the
Encyclopédie
Médico-Chirurgicale in 1965. Returning
to the old concept of yawning as a modified
respiratory act, he clearly identified it as
originating in the diencephalon and the
brainstem. After cataloguing all the causes
of excessive yawning, he concluded: "Yawning
is the most suggestive sign of
mesodiencephalic distress. It has
considerable prognostic value as a synonym of
gravity."
The age of pharmacology began in 1963
with publications on the experimental
activation of yawning, always associated with
erection and often with stretching of the
limbs in rats, cats and mangabey monkeys. In
Les Annales de l'Académie des Sciences
de New York, W. Ferrari and GL. Gessa et al.
published the results of intracerebral
injection of ACTH, a pituitary hormone
stimulating the secretion of cortisol and
other adrenocorticoids. ACTH, a peptide with
41 amino acids, is produced from a precursor
(proopiomelanocortin or POMC) and acts on the
paraventricular nucleus of the hypothalamus.
But POMC is also the precursor of other
hormones such as alpha-MSH, which stimulates
melanogenesis. These hormones were shown to
activate yawning after cortical injection.
The central role of the paraventricular
nucleus in the hypothalamus was identified in
1980 by the work of W. Ferrari, A. Argiolas,
and MR. Melis in Italy, as well as R.
Urba-Holmgren and B. Holmgren in Mexico. This
transformed the approach to the dopaminergic
and cholinergic systems in the brain.
During the 80s and 90s, American
psychologists R. Provine, and R. Baenninger
published the first scientific work on the
behavioural study of yawning, based on
observations of their students. Ethnologists
BL. Deputte in France and F. Troisi in the
Netherlands, working with no apparent
connection or consultation, described
different types of yawning in non-human
primates, notably testosterone-dependent
yawning in dominant males.
Today, at the start of the 21st
century, the neurohormonal mechanisms appear
to be established, making yawning a marker of
activity in D3 dopamine receptors. The study
of "contagious" yawning offers an example of
non-verbal language that is part of the
theory of mind. Observations such as the lack
of yawning in autistic children together with
brain imaging studies are changing the
neuropsychological approach to involuntary
decoding of emotions, bringing yawning closer
to empathy.
Having been associated with forced
ventilation for centuries, yawning has become
an emotional stereotypy exteriorising
homeostatic phenomena in the systems
controlling arousal, hunger and
sexuality.
References
1°) Mencken HL. Treatise on Right
and Wrong. New York. AA Knopf. Ed. 1934.
2°) Hippocrate. Of Flatus. The
Writings of Hippocrates and Galen. Epitomised
from the Original Latin translations, Coxe
JR. Philadelphia. Lindsay and Blakiston,
1846.
3°) Hippocrate. On the Nature of the
Bones, On the Reduction of Fractures and
Luxations. The Writings of Hippocrates and
Galen. Epitomised from the Original Latin
translations, Coxe JR. Philadelphia. Lindsay
and Blakiston, 1846.
4°) Littré E. 0euvres
d'Hippocrate. Baillière JB. Ed. Paris
1853.
5°) Hippocrate. Des vents, De
Flatibus. Oeuvres complètes. Tome V.
texte établi par J. Jouanna. Paris Les
Belles Lettres. 2003.
6°) Pline l'Ancien. Naturalis
Historiae Libri XXXVII. Ex editione Gabrielis
Brotier. Volumen Tertium. Londini. Imprimente
AJ. Valpy. 1826.
7°) Lapehn JD. De Oscitatione in
Enixu. Thèse soutenue devant JG.
Roederer. Litteris Pockwitzii et Barmeieri.
Ed. Göttingen 1758.
8°) Sénèque. Une
introduction, suivie de la lettre 70 des
Lettres à Lucilius P. Veyne. Ed.
Tallandier. Paris 2007.
9°) Oribase, ?uvres d'. Bussemaker
et Daremberg. Tome 3. Imprimerie
Impériale. Paris 1858.
10°) Fernelii J. Universa medicina,
cum notis, observationibus et remedÿs
secretis. Van Heurne, Otto (dit Heurnius).
Trajecti ad Rhenum : typis G. a Zijll et T.
ab Ackersdijck, 1656.
11°) Lommius ou Van Lom J.
Medicinalium observationum libri tres.
Antwerpioe. G. Sylvius. 1560.
12°) Duffin J. Jodocus Lommius's
Little Golden Book and the History of
Diagnostic Semeiology. J the Hist Med All
Sci. 2006 61:249-287.
13°) Hechstetteri P. Rararum
Observationum Medicinalium Decades tres
continentes, historias medicas, theorica
& practica varia. Vindelicorum A. Ed.
1624.
14°) Dupleix S. La curiosité
naturelle rédigée en questions.
Sonnius Cl. Ed. Paris 1626.
15°) Sanctorius S. La
médecine statique ou l'art de
conserver la santé par la
transpiration, traduite en français
par Le Breton. Briasson Ed. Paris. 1726.
16°) Eknoyan G. Santorio Sanctorius
(1561-1636) - founding father of metabolic
balance studies. Am J Nephrol.
1999;19:226-233.
17°) Descartes R. L'Homme et la
formation du f?tus. Angot Ch. Ed. Paris
1664.
18°) Senerti D. Operum. Tomus
Primus. Huguetan A. Sc. Lugduni 1666.
19°) Van Helmont JB. Les ?uvres
traitant de médecine et de physique,
dans la traduction de Le Conte J. Huguetan JA
& Barbier G. Ed. Lyon. 1671.
20°) Boerhaave H. Praelectiones
Academicae. Vandenhoeck A. Imp.
Göttingen 1739.
21°) Beutler JB. De Oscitatione.
Fleischerl C. lib. Lipsiae 1685.
22°) Hermann G. De Oscitatione et
pandiculatione. Kohlesii G. Imp. 1720.
23°) Brisseau P. Traité des
mouvements simpathiques. Henry G. Imp.
Valenciennes 1692.
24°) Cheyne G. The english malady:
treatrise of nervous diseases of all kinds.
Strahan G. Imp. London 1733.
25°) Gorter de J. De perspiratione
insensibili. Editio secunda Italica.
Manfrè J. Imp. Patavii 1755.
26°) Haller von A. Elementa
physiologiae corporis humani. edito secunda.
Pott JH. Imp. Lausannae 1777-1778.
27°) Hartley D. Explication physique
des sens, des idées et des mouvements
tant volontaires qu'involontaires.
Delaistre-Godet. Lib. Reims 1755.
28°) Smith CU. David Hartley's
Newtonian neuropsychology. J Hist Behav Sci.
1987;23:123-136.
29°) Webb ME. The early medical
studies and practice of Dr. David Hartley.
Bull Hist Med. 1989;63:618-636.
30°) Porée CG. Essay sur le
bâillement. Mémoire de
l'Académie des Belles-Lettres de Caen,
séance du 5 février 1756. Caen
1757.
31°) Raulin J. Traité des
affections vaporeuses du sexe. Herissant JT.
Lib. Paris 1758.
32°) Dufieu JF. Traité de
physiologie. Jacquenod CM Fils. Lib. Lyon
1763.
33°) Le Vacher de la Feutrie AF.
Dictionnaire de chirurgie. Lacombe. Lib.
Paris 1767.
34°) Boissier de Sauvages de Lacroix
F. Nosologica methodica sistens morborum
classes. Fratrum de Tournes. Amstelodami
1768.
35°) Tissot S. Traité des
nerfs et de leurs maladies. Didot PF. Imp.
Paris 1778.
36°) Tissot S. De la santé
des gens de lettres. Didot PF. Imp. Paris
1769.
37°) Karbowski K. Samuel Auguste
Tissot (1728-1797). J Neurol. 2001
Dec;248:1109-1110.
38°) Whytt R. Traité des
maladies nerveuses, hypochondriaques et
hystériques. Didot F. Lib. Paris
1777.
39°) Pearce JM. Robert Whytt and the
stretch reflex. J Neurol Neurosurg
Psychiatry. 1997;62:484.
40°) Darwin E. Zoonomia or the laws
of organic life. Johnson J. Ed. London
1801
41°) Lavater CJ. L'art de connaitre
les hommes par la physionomie. Depelafol Lib.
Paris 1820.
42°) Magendie F. Essai sur le voile
du palais, avec quelques propositions sur la
fracture du cartilage des côtes.
Thèse n° 21, soutenue le 27 mars
1808. Didot Jeune. Imp. Paris 1808.
43°) Legallois JJC.
Expériences sur le principe de la vie
notamment sur celui des mouvemens du c?ur, et
sur le siège de ce principe. Paris,
Chez d'Hautel, 1812.
44°) Landre-Beauvais AJ.
Sémiotique ou traité des signes
des maladies. Brosson JA. Lib. Paris
1815.
45°) Panckoucke CL. Dictionnaire des
sciences médicales. Panckoucke ED.
Paris 1812.
46°) Double FJ. Sémiologie
générale ou traité des
signes et de leur valeur dans les maladies.
Croullebois Lib. Paris 1817.
47°) Richerand A. Elémens de
physiologie. Paris. Caille et Ravier.
1817.
48°) Adelon N. Dictionnaire de
médecine et de chirurgie pratiques.
Paris. Gabon, Méquignon-Marvis, JB
Baillière, Crochard. 1829-1836.
49°) Good JM. The study of Medicine.
London. Thomas and George Underwood.
1829.
50°) Dureau de la Malle A. Annales
des Sciences Naturelles. Paris. Crocahrd.
1831.
51°) Joly-Mascheroni RM, Senju A,
Shepherd AJ. Dogs catch human yawns. Biol
Lett. 2008;4:446-448.
52°) Broussais F. Traité de
physiologie appliquée à la
pathologie. Baillière JB. Lib. Paris
1834.
53°) Abercrombie J. Pathological
& practical researches on diseases of the
brain and the spinal cord. Edinburgh: Printed
for Waugh and Innes, 1828.
54°) Flourens PM. Recherches
expérimentales sur les
propriétés et fonctions du
système nerveux dans les animaux
vertébrés. Baillière JB.
Ed. Paris 1842.
55°) Delasiauve L. Traité de
l'épilepsie. Masson V. Ed. Paris
1854.
56°) Herpin Th. Des accès
incomplets d'épilepsie.
Baillière JB. Ed. Paris 1867.
57°) Eadie MJ. The epileptology of
Théodore Herpin (1799-1865).
Epilepsia. 2002;43:1256-1261.
58°) Brachet JL. Physiologie
élémentaire de l'Homme.
Germer-Baillière ED. Paris et Savy
Lib. Lyon 1855.
59°) Lepelletier de la Sarthe A.
Traité complet de physiognomonie.
Masson V. Ed. Paris 1864.
60°) Lavater CJ. L'art de connaitre
les hommes par la physionomie. Depelafol Lib.
Paris 1820.
61°) Dumont M. The social success of
a false science: the physiognomy of Johann
Kaspar Lavater. Actes Rech Sci Soc.
1984;(54):3-30.
62°) Luys J. Recherches sur le
système nerveux
cérébro-spinal, sa structure,
ses fonctions et ses maladies.
Baillière JB. Ed. Paris 1865.
63°) Charcot JM. Leçons du
lardi à La Salpêtrière.
Bureaux du Progrès Médical et
Delahaye A. Ed. Paris 1887.
64°) Gilles de la Tourette, Huet,
Guinon. Nouvelle Iconographie de La
Salpêtrière. Tome 3. Lecrosnier
et Babé. Ed. Paris 1890.
65°) Gilles de la Tourette G.
Traité clinique et
thérapeutique de l'hystérie
d'après l'enseignement de La
Salpêtrière. Plon, Nourrit. Imp.
Paris 1895.
66°) Féré C. Note sur
le bâillement. Comptes-rendus de la
société de biologie (Paris).
1905;2:11-12.
67°) Mantegazza P. La physionomie et
l'expression des sentiments. Alcan F. Ed.
1897.
68°) Russell H. Yawning. Delsarte
Series N°1. US Book Company. Ed. New
York 1891.
69°) Trautmann A. Le
bâillement. Thèse n°40
soutenue le 20 décembre 1901. Imp du
Midi. Bordeaux 1901.
70°) Vigouroux A et Juquelier P. La
contagion mentale. Douin O. Ed. Paris
1905.
71°) Pike FH. An apology for
yawning. Journal of Heredity.
1916;7:447-449.
72°) Hughlings Jackson J. Yawning.
The Lancet. 1905;Janv 21:174.
73°) Von Economo C. Encephalitis
lethargica and its sequelae and treatment.
Oxford Medical Publications. London
1931.
74°) Sicard JA et Paraff A. Fou rire
syncopal et bâillements au cours de
l'encéphalite
épidémique. Bulletins et
Mémoires de la Société
Médicale des Hôpitaux de Paris.
1921;45:232-233.
75°) Levy G. Contribution à
l'étude des manifestations tardives de
l'encéphalite
épidémique. Vigot Ed Paris
1922.
76°) Hall Arthur. Epidemic
encephalitis. Bristol. John Wright and Sons.
1924.
77°) Jelliffe SE. Postencephalitic
Respiratory Disorders. New York. Nervous and
Mental Disease Publishing Company. 1927.
78°) De Saussure R. Discussion sur
l'étiologie d'un tic survenu quinze
mois après une encéphalite
léthargique atypique. Archives Suisse
de Neurologie et de Psychiatrie.
1923;12:292-317.
79°) Guillin G, Mollaret P. Les
séquelles de l'encéphalite
épidémique. Paris. Doin G.
1932.
81°) Dumpert V. Zur Kenntnis des
Wesens und der physiologischen Bedeutung des
Gähnens. J für Psychologie und
Neurologie. 1921;27(1-2): 82-95.
82°) Delmas-Marsallet P. Le signe du
bâillement dans les lésions du
cerveau frontal. Oto-Neuro-Ophtalmologie.
1937(15):183.
83°) Heusner AP. Yawning and
associated phenomena. Physiological Review.
1946;25:156-168.
84°) Barbizet J. Yawning. J Neurol
Neurosurg Psychiat. 1958;21:203-209.
85°) Furtado D. Consideraçoes
sobre o bocejo (a proposito de um caso
clinico). Gazeta Médica Portuguessa.
1949;1:983-989.
86°) Montagu A. On Yawning. JAMA.
1962;732:152.
87°) Boudouresque J, Pache R et
Khalil R. Troubles réflexes
viscéraux. EMC. fev
1965.17102D10.
88°) Ferrari W, Gessa, GL, Vargiu L.
Behavioral effects induced by
intracisternally injected ACTH and MSH. Ann
NY Acad Sci. 1963;104:330.
89°) Urba-Holmgren R, Gonzalez RM,
Holmgren B. Is yawning a cholinergic
response? Nature. 1977;267:261-262.
90°) Provine RR, Tate BC, Gelmacher
LL. Yawning : No effects of 3-5% CO2, 100% O2
and exercice. Behavioural and Neural Biology.
1987;48:382-393.
91°) Baenninger R, Binkley S,
Baenninger M. Field observations of yawning
and activity in Humans. Physiol
Behavior. 1996;59:421-425.
92°) Deputte BL, Johnson J, Hempel
M, Scheffler G. Behavioral effects of an
antiandrogen in adult male rhesus macaques
(Macaca mulatta). Horm Behav.
1994;28:155-164.
93°) Troisi A, Aureli F, Schino G,
et al. The influence of age, sex, rank on
yawning behavior in two species of macaques.
Ethology. 1990;86:303-313.
