- -Barbizet
J Yawning J Neurol Neurosurg Psychiat 1958;
21; 203-209
- -Barbizet
J Le bâillement Le Concours
Médical 1958; 80; 5; 537-548
- -Barbizet
J Bâillement et vigilance Revue de
gérontologie juin 1959
- -Bromage PR Yawning
BMJ 31/01/1959 p304
-
- Halfway between a reflex and an expressive
movement yawning is a very commonplace
phenomenon. Perhaps this is the reason why one
searches in vain for a paper on this subject in
text-books of contemporary physiology or
psychology and that one, must be content with
the brief definition in the dictionary that
"yawning is a deep inspiration made voluntarily
with a wide open mouth".
-
- Many
authors since Hippocrates, who seems himself
to have been interested in the question, have
studied either certain aspects or the whole
problem. An excellent historical survey of the
past knowledge about yawning may be found in the
thesis of Trautmann
(1901), where are reported the opinions of
Galen, Oribase, Sanctorius, Femel (1610), Kruger
(1627), Sennert
(1666), Boerhaave
(1680), Gartner (1736), Albertini (1737), Gunz
(1738), Czerniewski (1749), Buchner (1758),
Roederer (1759) Haller
(1766), Walther (1775) Double(1817),
Adelon (l 821),
Rothmund (1824), Richerand
(l 825), Muller
(1851), Monneret
(1861), Longet
(1868), Dechambre
and Charcot.
-
- In the twentieth century more papers have
been written, among others by Hauptmann (1920),
Dumpert (1921), Mayer (1921), Insabato
(1928), Peiper (1932), Moore
(1942), and Salmon
(1948). Two good critical reviews are those
by Heusner (1946) and
Boudouresques
(1950).
-
- The
zoologists have not remained indifferent,
and they teach us that yawning may be observed
in the primates and the carnivores. It is often
accompanied by stretching. It is not observed in
herbivores. It is difficult to specify its
significance, and the connexion between yawning
and the movement of opening the mouth that may
be observed in fishes, reptiles, and amphibians.
The same may be said of the movements made by
the birds beak accompanied by flapping of the
wings. Therefore our study shall remain limited
to man.
- Analysis of
Yawning
-
- Yawning is an involuntary, paroxysmal
breathing movement. It is a motion unfolding
itself in a certain order, wherein three phases
may invariably be distinguished: the first one
is active and inspiratory; the second phase
corresponds to the acme; the third is passive
and expiratory. Their respective duration is
about 1-5 to 4 sec. each. An average yawn lasts
from 4 to 7 sec.
-
- An analysis of the subject's movements may
be made by a clinical survey or by the study of
radiographs taken every half second, as we have
done at St. Antoine Hospital with Dr.
Chalut.
-
- In the first phase we see the progressive
opening of the mouth, the dilatation of the
pharyngo-larynx and of the thorax, and the
lowering of the diaphragm. The opening of the
mouth is very slow, and the mouth is still half
open when the dilatation of the pharynx and the
larynx is already at its maximum.
-
- The lowering of the neck's air axis is
obvious from simple inspection, which shows the
lowering of the thyroid cartilage. A radiograph
shows that the body of hyoid bone, which stands
at rest at the level of C.2-3 vertebrae goes
down to C.6-7, and explains the tongue's
situation as it is pulled backward and downward,
the tip going well away from the teeth. The
dilatation of the glottis and the abduction of
the vocal cords can be verified by a
laryngoscopic examination sufficiently long
continued to catch a spontaneous yawn. The
radiographs have shown that the dilatation of
the pharynx is enormous and surprising, for it
increases to three or four times its normal
size. The pharynx, larynx, and trachea, as well
as the bronchial tubes, appear very dilated on
the plates. While the opening of the mouth and
the deep inspiration may be observed in many
cases apart from yawning, the enormous expansion
of the pharynx with the lowering of the hyoid
bone and of the tongue is peculiar to
yawning.
-
- It is to be noted that the inspiratory sound
observed in yawning is produced in the palate
and the throat's isthmus. It is not a glottal
noise, the glottis being dilated to its utmost
at this phase.
-
- The second phase of yawning corresponds to
the acme of the mouth's opening and to that of
the pharyngeal and thoracic dilatation. Certain
predisposed subjects may even at this point
dislocate the jaw. At this moment appear the
facial modifications which began at the end of
the first phase. Contraction of the lip dilators
exaggerates the mouth's opening and contraction
of the eyelids causes a partial or even a total
occlusion of the eyes. The nostrils are dilated.
The skin at the base of the nose wrinkles and
the eyebrows are lifted. At this phase there may
also be a degree of tonic contraction of the
extensor muscles of the neck and of the trunk,
and may extend to include hyperextension of the
limbs. The stretching, which is far frorn
constant, has the result of increasing the
thoracic capacity. Tears may be secreted, and
less frequently saliva.
-
- The third phase is passive. The inspiration
ceases abruptly. Expiration is slow and noisy,
followed by the sound - aah - originated by the
larynx. The pharynx goes back to its normal
size, the mouth c oses itself, and the face
resumes its usual aspect.
-
- This group of complex and synergic motions
constitutes yawning. However, yawning may be
accompanied by other motions emphasizing or
minimizing its action. Yawning may be
exaggerated and emphasized by stretching of the
limbs, or by a modulation of breathing, or by
the execution of rhythmic lateral motions of the
mandibles.
- Yawning can also be repressed to a certain
extent in circumstances where it would
constitute bad behaviour; the subject puts his
hand before his mouth. He can also repress a
yawn by stopping the mouths opening and
controlling the inspiratory motion. But, in
spite of efforts, yawning is often betrayed by
such a gesture, and a stifled yawn does not
escape a careful observer. In this case yawning
may be reduced to the action of the pharynx,
which once more shows the importance of this
phase.
-
- Certain physiological observations have been
made during yawning, but they offer small
reward. There may be a slight acceleration of
the heart in the inspiratory phase with a fall
in the index of capillary oscillations in the
finger tips. This phenomenon is of no great
importance, as it may also be observed during
deep inspiration (Heusner,
1946). An E.E.G., if performed in the act of
yawning, cannot be interpreted owing to
interference by movements and muscle
action.
- It is noteworthy that a yawn is rarely
isolated. It usually occurs in fits of two or
three. The intensity of the yawn often
increases, and each yawn is separated by a few
regular breaths. Sometimes, the yawns will be
repeated, irregularly, during several
minutes.
-
- Yawning and
Stretching
-
- These two actions are often but not always
associated. Stretching is connected with the
second phase of yawning. Infants and animals
stretch and yawn often at the same moment. In
adults, stretching is usually observed in the
period of awakening. The association of these
two motions is far from constant. Yawning, even
excluding cases where stretching is repressed by
good manners, is often isolated. Likewise,
stretching after a long period in the same
position is not accompanied by a yawn. These
facts allow us not to give quite the same
physiological interpretation to these motions,
especially as we shall sec in the case of
theïr functional value.
-
- The Cause of the
Yawn
-
- Tey are numerous causes, which may be
classified in three categories, physiological,
pathological, and experimental.
- Physiological.-Drowsiness must be
mentioned first; men and animals yawn when they
are sleepy. They yawn also when they emerge from
sleep. Some persons are subject to yawning and
stretching when they awake.
-
- Boredom is a frequent cause. It can be the
consequence of different circumstances-a dull
talk, a tedious lecture, a wearisome book.
Weariness is intimately connected with a lack of
interest fundamental to the genesis of
yawning.
- Seeing others yawning is infectious -
Interdum tamen sola imaginatio ossitationis
causa est. Cum enim qui videt alium oscitare,
ipse quoque ad oscitandum invitatur - quoted
Sennert in
1666.
-
- "One
yawn brings seven" is a popular saying.
-
- It is easy to make oneself yawn. Four or
five deep inhalations with a wide open mouth,
imitating spontancous yawning, provoke yawning.
Once the spontaneous yawn has begun, it will
seldom remain isolated, and during the following
quarter of an hour will be followed by new
isolated yawns or by a fit of yawning.
-
- Hunger or, the contrary, the plenitude after
a heavy meal, are generally admitted as inducing
yawning. In the second case yawning is
associated with drowsiness. Certain plethoric
patients seek medical advice for these
poat-prandial yawns.
- Yawning is frequent in certain
circumstances, such as physical weariness or
pregnancy.
-
- Pathological
-
- Yawning is commonly observed in lesions of
the brain-stem. It can also be seen in intrinsic
lesions (haemorrhage, softening, tumours), and
in compressions (posterior fossa tumours). It is
noteworthy to recall that drowsiness is a
symptom of peduncular softening
(Lhermitte).
-
- If yawning is commonly observed in
hemispheric tumours, especially frontal and
temporal tumours, and in hemispheric
haemorrhage, it is probably due to indirect
compression of the brain-stem provoked by
intracranial hypertension or a temporal
herniation. In such cases a yawn serves as an
indication of a brain stem lesion and bears a
bad prognosis
- In the course of diffuse lesions of the
brain, yawning is not infrequent. It bas been
observed in cases of alcoholic encephalopathy
and of general paralysis of the insane.
-
- Yawning is frequent in respiratory sequelae
to encephalitis lethargica, together with sighs
and spasmodic hiccup. Sicard
and Paraf (1921) and Turner and Critchley
(1925) mention spasmodic yawning and gaping.
Choreics also yawn. Yawning can be observed in
certain varieties of epilepsy. Wilson (1940)
interprets yawning as an "aura" of visceral
crisis.
-
- Penfield and Jasper (1954) mention two
observations of yawning as an element of
autonomie diencephalic seizures. They cite the
case of a woman of 29 with a large astrocytoma
occupying the whole left temporal lobe and the
lower portion of the corpus striatum, whose fits
started abruptly with occipital pain
accompanied by yawns and hiccups while at
the same moment the left arrn and the left side
of the mouth became numb. The fit ended with a
need to urinate.
-
- Yawning has been described very often and
with many details as a manifestation of hysteria
(Charcot, Dejerine).
- Salmon (1948) points out that fits of
yawning may be a sign in myasthenia gravis and
quotes one of his personal cases and one of
Albertoni's. He indicates the action of
prostigmine in stopping yawning. Yawning is also
noted in the course of anaemia, haemorrhage, and
shock, and during pyrexia, as well as in
digestive disturbances, though no one has tried
to explain its mechanism in this case.
-
- Yawning and Cerebral
Stimulation.
-
- A comparison is possible between the natural
causes of yawning and yawning created
experimentally by intracerebral stimulation, but
we do not know of any research work. On the
other hand, yawning bas been studied and noted
in certain protocols. Hess (1938), by
stimulating the intralaminar substance of the
thalamus and the posterior subthalamus, has
induced sleep in cats after fits of yawning. The
experiments of Passouant, Passouant- Fontaine,
and Cadilhac (1956) on the stimulation of the
rhinencephalon, and particularly of Ammon's
horn, also mention yawning. The induced crisis
bas three phases: during stimulation, reaction
of escape, and during the postdischarge period,
uneasiness with a diminution of watchfulness. In
the third phase the animal stands, licks itself,
purrs. This manifestation of well-being lasts a
few minutes, and sometimes the animal lies down,
stretches, yawns and goes to sleep.
-
- Sleep may start three or four minutes after
the discharge. An E.E.G. of the hippocampus
shows that it is preceded by sharp waves with
increased voltage. It is obvious in this case
that yawning is only a late and indirect
manifestation of stimulation. We must remember,
however, that it is integrated in a behaviour of
well-being and sleepiness opposed to the
reaction of escape simultaneous with
stimulation.
-
- The fact that yawning may be observed during
the stimulation of the rhinocephalon or
hypothalamus, formations which are functionally
and intirnately joined with the reticular
activating system, must be emphasized.
- Linked Yawning and Stretching.-In
normal subjects yawning and stretching may be
independent of one another, but in some
pathological conditions they are tightly linked.
Dumpert (1921) and Lewy (1921) refer to the
clinical observation of hemiplegic
patients in whom yawning was attended by
stretching the paralysed arm. Heusner
(1946) also mentions spontancous stretching
of the paralytic arm provoked by a yawn.
-
- Physiology of
Yawning
-
- While the clinical aspects and the
determining causes of yawning are well known,
its physiological mechanism is no better known
than its significance. Besides the fanciful
interpretations aiready mentioned, a certain
number of theories have been brought forward
that may be classified in two groups according
to whether the yawn is a secondary or a primary
disturbance.
-
- In the first group yawning is considered as
a mechanism of regulation, just as shivering is
considered as an automatic reaction opposed to
the cooling of the organism. No agreement has
been reached, however, either on the nature or
on the mechanism of this regulation.
-
- Hauptmann (1920) suggested that yawning and
stretching were opposed to muscular hypotonia
which, like boredom, is the consequence of the
inactivity of superior brain centres. Salmon
(1948) maintains that yawning is an
automatic reaction of the respiratory muscles
caused by hypotonia of the respiratory bulbar
nerves and by the hypotonia that follows sleep.
But Dumpert (1921) went farther in this
hypothesis. He considers that yawning occurs
when the brain circulation is not sufficient to
maintain wakefulness and vigilance. Yawning and
stretching should increase venous circulation to
the heart first by compressing the veins of the
trunk and the limbs as well as the splanchnic
veins; secondly, by diminishing the
intrathoracic pressure. The resulting venous
hypertension increases the cardiac output
(Bainbridge's reflex) and consequently improves
arterial irrigation. The brain circulation
benefits especially, and, further, the sensory
stimuli from the stretched muscles produces,
according to Dumpert, system vasoconstriction
and vasodilatation of cerebral arteries.
Stretching, and to a lesser degree yawning,
might thus produce an increase of blood
ciculation sufficient for the maintenance of
wakefulness.
-
- Among the functional theories of yawning,
the hypothesis quoted by Heusner
(1946) of a secretion of thyroxin determined
mechanically by the compression of the thyroid
gland during yawning should be mentioned.
-
- Beside these resolutely finalist theories,
some authors neglect the physiological
consequences of yawning and consider it as an
accident connected with cerebral strain (Mayer
1921), just as crying and laughing are the
expressions of pain or joy.
- For Peiper (l 932), yawning is a transitory
disorder of the respiratory centres, weariness
producing a decrease of the excitability of the
superior respiratory centres liberating an
underlying centre for yawning.
-
- These theories, without being completely
opposed, are based on unverified or disproved
physiological hypotheses, such as the increase
of venous pressure during yawning or the
decrease of the cerebral blood flow when
wakefulness ceases. They still leave unexplained
certain aspects of the psychomotor reflex
described as yawning.
-
- In the light of contemporary knowledge of
psychophysiology, it is possible to attempt an
explanation of the mechimism of yawning, while
nevertheless underlining the gaps open to
further research.
-
- The Mechanism of
yawning
-
- Yawning is a complex, involuntary, and
paroxysmal act. Under the influence of a certain
number of facts, a brief (4 sec. to 7 sec.)
motor activity takes place, bringing into play a
great number of thoracocervico-facial muscles.
This suggests a critical activity spreading from
one place to another in a given neuronal
circuit. With the knowledge of the muscles
participating in yawning, it is possible to
state that the motor nuclei involved are located
in the bulb and in the cervical cord. It is
therefore possible to state that yawning, or
more exactly the motion of the yawn, is
connected with a paroxysmal discharge involving
a certain number of motor nuclei situated in the
bulb and in the cervical cord. The extension of
this discharge to the nuclei of the trunk and
the limb muscles induces stretching.
-
- It seerns impossible to specify whether
there exists a hierarchy in this neuronal
structure which would allow us to locate a
centre of yawning. But, on the other hand, we
may note that this structure has a close
relationship to both the reticular formation and
the cerebral cortex. The brain-stem reticular
formation appears, according to a large number
of studies of Magoun (1950) and of Moruzzi and
Magoun (1949), to be capable of modifying the
central excitatory state, and thus of
controlling the degree of alertness. it
determines the level of consciousness in its
arousal capacities, alertness declining in sleep
and in pathological states related to sleep
(drowsiness, torpor), and disappearing only in
deep coma, and, on the contrary, increasing in
varying degrees according to the intensity of
stimulation and, probably, to the extent of the
nervous mechanism set in motion.
-
- Participation of the cerebral cortex cannot
be contested when yawning is the result of
complex psychic activities such as imitation or
boredom. It is interesting to recall in this
connexion the experiences of French,
Hernandez-Peon, and Livingston (1955) showing
that efferent pathways issuing from the cerebral
cortex appear to project down to the reticular
formation.
-
- If we maintain this hypothesis, which should
be verified, particularly by recording the
neuronal activity of the nuclei set in motion by
yawning with intrabulbar electrodes, the
standard E.E.G. being uninformative, we must
answer the following question: Which are the
responsible factors in the paroxysmal discharge
in this bulbo-medullary motor structure ?
-
- Circulatory and Humoral
Factors
-
- These must first be discussed because they
have generally been invoked though without any
accurate experimental data.
-
- The frequency of the yawn in the course of
anaemia or circulatory insufficiencies invokes
the possibility of bulbar anoxia or modification
of the C02/02 ratio. We lack precise facts on
this subject, but we can observe that voluntary
apnoea, even if it lasts some time, does not
cause yawning. There is no proof that a slight
variation of bulbar circulation will carry with
it anoxia. On the contrary, we know the part
played by Hering's nerve and the carotid sinus
in the regulation of cerebral circulation as
well as the constancy of this circulation under
physiological conditions. Furthermore, one does
not observe yawning when the central cerebral
circulation is insufficient, as in the
paroxysmal fits of bradycardia in the course of
the Stokes-Adams syndrome.
-
- Some authors also mention the part taken by
humoral modifications. Yawning and post-prandial
drowsiness may be attributed to an alkalotic
wave or a discharge into the blood of
polypeptids or lipids of digestive origin. It
could also be produced by intermediary
metabolites due to muscular strain. Cramer
(1924), noting the frequency of yawning in
patients with colitis, assumed that it was due
to an auto-intoxication by bacteriological
toxins produced in the bowel. In fact, the
existence of an endogenous origin has not been
proved any more than that of an endogenous
hypnotic substance.
- Pharmacology provides, on the contrary,
drugs predisposing to the appearance of yawning
and of drowsmess, as is the case with morphine
and hypnotics. The action of these substances on
the reticular formation is well known, whereas
caffeine and amphetamine have an opposite
effect. In conclusion, if yawning can be induced
by pharmacological means, there is no formal
proof of the part taken by circulatory or
humoral disturbances in the genesis of
yawning.
-
- It must be noted that if such disturbances
exist, which remains; possible and must be the
subject of further studies, they could only be
an adjuvant cause, their duration clearly
exceeding the duration of yawning, which may or
may not appear in instances such as after meais,
according to the psychological condition of the
subject.
-
- Psycho-sensorial
Factors
-
- Spontaneous yawning must be distinguished
from yawning by imitation. Both are influenced
by the surrounding circumstances, but in
different ways.
-
- Spontaneous yawning occurs in particular
physiological circunstances such as weariness or
sleepiness. In these cases, the subject lacks
interest in his surroundings and spontaneous
thought diminishes. On the contrary, one does
not yawn and even if one is drowsy, one awakes
if a new stimulus abruptly appears. It may be
physical stimulation or affective shock which
rouses attention. People do not yawn at the very
moment they learn the result of an important
examination or the news of an accident to a
relative. Yawning only occurs in psychological
conditions of indifférence or lack of
interest in surroundings.
-
- Knowing the part played by the reticular
formation in the mechanism of wakefulness, we
propose the following hypothesis. Yawning is an
integrated discharge in a bulbo-reticular rnotor
structure occurring at a particular level of
activity of the reticular formation
corresponding to a decrease of wakefuiness
preceding sleep. This hypothesis, which is in
agreenient with neurophysiological and
pharmacological principles, explains why yawning
may be observed when a subject begins to sleep
as well as when he awakens. In our opinion,
yawning appears as a physical manifestation of a
drop in wakefulness. This paroxysmal motor
discharge may be compared with the muscular
hypotonia observed during sleep. It is the
expression of a mode of being and does not
constitute a reaction against it. It should not
play any physiological part. In fact, yawning,
as we know, induces yawning and does not induce
wakefulness. Yawning should be distinguished
from stretching, which perhaps has the function
of setting wakefulness in motion.
-
- Yawning by imitation may occur in certain
circumstances of release of interest, but the
fact that it can be induced shows that we
maintain a certain degree of consciousness in
our surroundings which involves some
participation of our system of wakefulness. The
infectiousness of yawning is only one example of
the numerous acts caused by imitation, often
quite unconsciously, for instance, repeating a
tune, raising or lowering one's voice according
to one's interlocutor, answering a grin by
another grin, or a smile by a smile. In the same
way, some expressive acts such as laughing or
crying are infectious in certain circumstances.
There is still much to discover in the mechanism
of association. However, the possibility of
associating two stimulations, two ways of
behaving, two ideas, is at the basis of
learning. Infectious yawning is just one
particular case in a series of imitative
gestures.
-
- It is also difficult to interpret the
mechanisrn which determines a real, spontaneous,
irrepressible yawn after a fit of false yawning.
The passage of a voluntary act to a paroxysmal
and involuntary one is difficult to interpret on
purely associative grounds, and one may wonder
to what extent the fact of yawning voluntarily,
by a mechanism which remains to be described
accurately, has not rnodified neuronal
excitability, thus facilitating the paroxysmal
and involuntary discharge.
-
- Psycho-social Significance of
Yawning
-
- Let us eliminate from this discussion
infectious yawning, an imitative gesture which
is proof of a normally suggestible subject and
of his psychological irresponsibility, and let
us return to spontaneous yawning.
-
- Without any physiological usefulness,
spontaneous yawning has still a psychological
significance: it shows lack of interest. This
psycho-physiological conception carries with it
certain considerations on the social
circumstances under which yawning occurs.
-
- Yawning has an expressive mimic value as
long as it indicates indifference and boredom.
The interest or lack of interest that we feel
for our surroundings certainly depends on the
nature of the surroundings. The interest of the
subject wili be very différently stirred
according to whether he is lying peacefully in
silence and in darkness, or whether experiencing
sensory or psychic stimulation. This applies to
infants as well as to adults. For the latter,
however, the interest lie feels for the exterior
world depends largely on his personality and his
former experience. Interest is conditioned by
different factors, such as family, school,
profession, social position. For instance, a
conversation on an unfamiliar topic, or
concerning an unknown person, causes lack of
interest. The same could be said of a discussion
in a foreign language. It is well known that a
connoisseur will bore the layman if he speaks at
length on an esoteric subject. To a certain
extent it is easy to know when the subject will
please or bore, one's taste representing exactly
what one is interested in. The intimate
connexion between interest and personality
explains the expressive value of yawning, which
appears as the mark of unconcern and
disinterest. It may be said that yawning is to
boredom what the gestures of laughing and crying
are to joy and sorrow.
-
- This interpretation of the significant value
of yawning agrees with the popular opinion that
yawning is a symptom of boredom. The fact that
it is polite to put one's hand before one's
mouth when yawning, that is, to hide a yawn, a
habit learned in childhood and which becomes
automatic to the point of being an integral part
of the yawn, is an implicit acknowledgement of
the social significance of that motion
expressing weariness and refusal, which it is
better to dissimulate.
-
- It is possible that in putting forward a
digestive trouble as an explanation of yawning
the subject unconsciously tries to hide the real
cause, boredom. As an involuntary expressive
gesture, yawning, is, however, a conscious
phenomenon te, which, in the course of its
automatic development, voluntary modulations may
bc added. For instance, a suppressed yawn shows
an endeavour to dissimulate boredom. On the
other hand, an emphasized yawn, long and noisy,
proves in an unequivocal manner that the subject
wants to show his weariness or even his
aggressive attitude to a situation for which he
does not feel any interest.
-
- Summary
-
- The different phases of the yawn are
described, while the physiological and
pathological causes are considered. The
classical - theories of yawning are discussed.
The following views are put forward:
- a) The yawn is connected with an integrated
discharge in a bulbo-cervical motor complex
which appears at a certain level of excitability
of the consciousness arousal system (reticular
brain-stem formation) corresponding to the
lessening of alertness preceding sleep.
- (b) This particular state of alertness
depends on sensory stimulations received from
the surroundings. It can also, be induced
experimentally by intracerebral electric
stimulation or by certain drugs (hypnotics). The
part played by endogenous factors (circulatory
or humoral), though often discussed, has never
been proved
- (c) On physiological grounds, yawning
appears as the physical manifestation of a
lowering of wakefulness, and does not seem to
have any physiological function.
- (d) From the psychological point of view,
yawning by imitation may be considered as one
particular case in the series of imitative
gestures. Spontaneous yawning, on the contrary,
may be included among the expressive gestures.
Interest as well as lack of interest is
intimately connected with the personality.
Yawning, which expresses boredom, unconcern, and
indifference to certain circumstances, has the
value of a refusal, and even in certain cases of
an unconsciously or consciously aggressive
attitude.
-
-
- Yawning
- PR Bromage
- BMJ 31/01/1959 p304
- Your annotation (Journal, December 27, p.
1585) on the article by Dr. Barbizet about
yawning does not quite cover all the ground.
There is the psychological conflict which Dr.
Barbizet hints at: the conflict between the need
to remain within an irksome environment and the
desire to escape from it (to sleep or other
activity). But aside from this there is also a
functional respiratory consideration.
-
- Yawning may be considered as a paroxysmal
sigh, combining the thoracic and abdominal
muscles of respiration with the phylogenetically
primitive glossopharyngeal elements. By thinking
of a yawn in this way, one aspect of its
functional significance may be clearer, for
occasional sighing is a regular and necessary
accompaniment to the muscular hypotonia of
sleep.
-
- Without an occasional sigh the compliance of
the chest falls and the work of breathing is
increased. This fall of compliance is readily
observed in cases of prolonged apnoea treated by
mechanical artificial ventilation. If a
pressure-controlled machine is used and the
pressure of the inspiratory phase is kept
constant for an hour or so a gradual fall of
tidal volume is observed. However, if a few
artificial sighs are interposed, by increasing
the inflating pressure for two or three breaths
(so that the tidal volume approaches the
inspiratory capacity), then the compliance
reverts to its previous level. Presumably the
act of sighing opens up alveoli which had become
shut by surface tension forces, restoring the
lung volume to its normal value.
-
- It is of some interest that this restoration
of compliance does not occur if the patient is
receiving noxious stimuli while under light
general anaesthesia, with or without complete
curarization. Here the attempted reaction is the
opposite of a sigh or a yawn, the patient
responding to noxious stimulation from without
by an expiratory rather than an inspiratory
effort.-I am, etc.,
- Reference
- Barbizet, J., J. Neurol. Neurosurg.
Psychiat., 1958, 21, 203.
- Bromage, P. R., Clin. Sci., 1958, 17,
217.
-
- Some
psychological aspects of yawning Moore J
1942
- Yawning: an
evolutionary perspective
- Le
bâillement, du réflexe à la
pathologie
- Neural
basis of drug induced yawning Cooper
SJ, Dourish CT in Neurobiology of Stereotyped
Behaviour
- New
Scientist: The Big Yawn 19 Dec 98 (pdf)
- Yawning
gaps Jim Horne
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