INSOMNIA;
AND OTHER
DISORDERS OF SLEEP.
BY HENRY M. LYMAN, A.M., M.D.,
Professor of Physiology, and of Diseases
of the Nervous System, in Rush Medical
College; Professor of Theory and Practice
of Medicine, in the Woman’s Medical
College; and Physician to the Presbyterian
Hospital, Chicago, Ill.
CHICAGO:
W. T. KEENER,
96 WASHINGTON STREET.
1885.
COPYRIGHT, 1885.
R. R. DONNELLEY & SONS, PRINTERS, CHICAGO.
PREFACE.
Tired Nature’s sweet restorer, balmy sleep.
--YOUNG.
The regularly recurring incidence of natural sleep forms one of the most
important subjects for physiological investigation. Were it an event of
rare occurrence, it would excite a degree of astonishment and alarm equal
to the agitation now experienced by the spectator of an ordinary attack of
syncope or of epileptic convulsion. But, so completely does the recurrence
of sleep harmonize with all the other facts of life that we are as
indifferent to its nature as we are to every other healthy function of the
body. It is only when the mind has undertaken a critical observation of
the bodily and mental changes which accompany and condition the phenomenon
that we begin to comprehend its wonderful character. Ushered in by a
waning activity of body and mind that no effort of the will can long
resist, nothing could more forcibly suggest the idea of approaching
dissolution if, from the very earliest period of unconscious infancy, we
had not been accustomed to the dominion of this imperious necessity. The
remarkable likeness between the fading of consciousness in sleep and its
extinction in death has, in all ages and among all people, arrested the
attention of poets and philosophers of every degree.
Soft repose,
A living semblance of the grave,
sang old Thomas Miller; and, describing, in Milton’s stately verse, the
close of his first day in the garden of Eden, Adam says:
Gentle sleep
First found me, and with soft oppression seized
My drowsy sense, untroubled, though I thought
I then was passing to my former state
Insensible, and forthwith to dissolve.
How wonderful is death,
Death and his brother, Sleep!
exclaims Shelley, echoing the marvellous strains that have come down to us
from the days of Homer and Hesiod. In that venerable literature Sleep and
Death are represented as twin brothers, sons of Night; dwelling in the
lower world of spirits, whence they come forth to perform the will of the
Olympian Gods.
The prosaic genius of our scientific generation no longer tolerates such
lively exercise of the imagination. The splendid anthropomorphism of the
Hebrew poet, looking out upon the silent night, and cheering his soul with
the sonorous exclamation,
Behold, he that keepeth Israel
Shall neither slumber nor sleep
* * * *
For so he giveth his beloved sleep,
has become a mere memory of childhood. Wordsworth understood the full
significance of this change when he wrote:
There was a time when meadow, grove, and stream,
The earth, and every common sight,
To me did seem
Apparelled in celestial light,
The glory and the freshness of a dream.
It is not now as it has been of yore;
Turn whereso’er I may,
By night or day,
The things which I have seen I now can see no more!
... I know, where’er I go,
That there has passed away a glory from the earth.
If, however, despite the loss of much that was beautiful and attractive in
the myths of antiquity, we take advantage of the
Years that bring the philosophic mind,
we shall surely find in the scientific investigation of sleep enough to
awaken “thoughts too deep for” words.
CONTENTS.
CHAPTER I. THE NATURE AND CAUSE OF SLEEP.
Definition of sleep--The invasion of sleep--The hypnagogic
state--Depth and duration of sleep--Diagrammatic
illustration of the phases of sleep--Modifications of
physiological functions produced by sleep--Effect of sleep
upon the processes of respiration, circulation,
calorification, secretion, and nutrition--Consequences of
the progressive invasion of the nervous system by sleep--
Effect upon the organs of special sense--Effects observed
in the muscular apparatus of the body--Condition of
intellectual functions during the invasion of sleep--Does
the mind ever sleep?--Arguments adduced by Sir William
Hamilton and others to prove the continued activity of the
mind during the sleep of the brain--Reasons for supposing
that the mind may sleep--Variability of the depth of
sleep--Experiments of Kohlshüter to estimate the degree of
variation--Alternation of day and night considered as a
cause of sleep--Diminution of sensation a cause of sleep--
Illustrative observation by Strümpell--Fatigue a cause of
sleep--Hypothesis of Obersteiner regarding the cause of
sleep--Hypothesis of Pflüger--Production of artificial
sleep by impregnation of the brain with narcotic
substances--Analogous production of natural sleep by
accumulation of cerebral waste-products--Observations
regarding the duration of sensory impressions requisite for
the excitement of conscious perception--Difference between
syncope and sleep--Observations of Mosso regarding the
state of the cerebral circulation during sleep--Cause of
the change in the cerebral circulation during sleep--
Molecular conditions necessary for the production of
sleep--Somnolence--Sleeping Dropsy, or Maladie du Sommeil--
Coma--Lethargy--Apparent death--Lucid lethargy. 1
CHAPTER II. INSOMNIA, OR WAKEFULNESS.
Causes of insomnia--Affections of the organs of special
sense--Effects of light--Effect of sound--Impressions upon
the organs of smell and taste--Disturbances caused by a
high temperature--Atmospheric and electrical disturbances--
Effects produced by cold--Hibernation of animals--
Disturbances of sleep occasioned by painful sensations--
Disorders of the sympathetic nerves--Morbid states of the
central nervous organs--Disorders of circulation and
nutrition--Hyperæmia of the brain--Anæmia and starvation of
the brain--Effects of tea and coffee--Effect of alcohol--
Inflammations, degenerations, and tumors affecting the
brain--Excitement of the brain by diseased conditions of
the blood. 38
CHAPTER III. REMEDIES FOR INSOMNIA.
Serious consequences of insomnia--Its relation to cerebral
diseases--Treatment of insomnia by moderation and control
of the cerebral circulation--Remedial agents--Nervous
stimulants and nervous sedatives--Heat--Baths--Massage--
Electricity--Counter-irritants--Food--Digitalis--Camphor--
Musk--Valerian--Cannabis indica--Belladonna--Hyoscyamus--
Stramonium--Phosphorus--Acids--Opium--Cold--Alcohol--
Paraldehyde--Ether--Chloroform--Chloral--Butylchloral
hydrate--Amyl nitrite--Opium and opiates--Bromides--Hops--
Gelsemium--Conium. 56
CHAPTER IV. TREATMENT OF INSOMNIA IN PARTICULAR DISEASES.
Insomnia in acute affections of the brain--In insanity--In
chronic alcoholism and delirium tremens--In diseases of the
heart and blood-vessels--In angina pectoris--In diseases of
the respiratory organs--In asthma--In renal diseases--In
diseases of the liver--In gastro-intestinal diseases--In
febrile conditions--In rheumatism and gout--In lithæmia--In
syphilis--In disorders of nutrition--During pregnancy and
after parturition--In spasmodic diseases--In childhood--In
old age. 92
CHAPTER V. DREAMS.
Physiology of perception and of dreaming--Definition of the
act of dreaming--Revery--Production of illusions and
hallucinations by drugs and by disease--Effects of
hasheesh--Effects of acute disease--Association of
ideas--Memory of past sensations--Dreams produced by
excitement of the different organs of sense--Persistence of
dream-impressions after waking--Experience of M.
Baillarger--Of Professor Jessen--Belief of savages in the
reality of dreams--Sensory dreams--Intellectual dreams--
Repetition of dreams--Incoherence of dreams--Cause of the
superior vividness of certain dreams--Duration of dreams--
Dreams excited by morbid states of the body--Prophetic
dreams--Their causes--Clairvoyant dreams--Hallucinatory
dreams--Sir Edmund Hornby’s experience--Hallucinations--
Case related by Dr. E. H. Clarke--Revelation through
dreams--Revival of memory in dreams. 116
CHAPTER VI. SOMNAMBULISM.
Causes of somnambulism--Physiology of somnambulism--
Varieties of the disorder--Maury’s classification--
Classification of Ball and Chambard--Diagrammatic
representation of their classification--Somnambulic
lethargy--Illustrative cases--Somnambulic dreams--Night
terrors--Somnolentia or sleep-drunkenness--Sleep-walking--
Illustrative cases--Condition of the special senses in
somnambulism--Relation of memory to the somnambulic
paroxysm--Illustrative cases--Occasional recollection of
incidents connected with the somnambulic dream--
Resemblances between the somnambulic state and the
condition of post-epileptic mania--Somnambulic visions--J.
P. Frank’s case--Mesnet’s case--Somnambulic life--Its
likeness with the double-consciousness of certain forms of
epilepsy--Illustrative cases--General theory of
somnambulism. 166
CHAPTER VII. ARTIFICIAL SOMNAMBULISM OR HYPNOTISM.
Antiquity of the phenomena of hypnotism--Modern
observations--Physical conditions favorable to the
phenomena--Methods of inducing the hypnotic state--Duration
of hypnotic sleep--Rudimentary states of hypnotism--
Investigations of the Society for Psychical Research--
Mind-reading--Physiological explanation of the process--
Charcot’s observations on artificial somnambulism--
Cataleptic variety of the hypnotic state--Lethargic
variety--Somnambulic variety--Hypnotic clairvoyance--
Exalted sensibility of the brain in hypnotic states--
Susceptibility to suggestions from without--Phenomena of
so-called spiritualism--Table-rapping--Planchette--
Therapeutical employment of hypnotism--Metaphysical healing. 212
CHAPTER I.
THE NATURE AND CAUSE OF SLEEP.
Worn out, friend, is every theory,
But green the golden tree of life.
--GOETHE.
Natural sleep is that condition of physiological repose in which the
molecular movements of the brain are no longer fully and clearly projected
upon the field of consciousness. This condition is universally observed in
all healthy animals; and its recurrence is intimately associated with the
diurnal revolution of the earth, and the succession of day and night. The
disappearance of daylight is, for the majority of living creatures, the
signal for cessation of active life. Though its onset may be for a time
delayed by an effort of the will, the need of rest at length overcomes all
opposition, and the most untoward circumstances cannot then prevent the
access of unconsciousness. The story of the sailor-boy, sleeping on “the
high and giddy mast,” is familiar to every one. An officer in the United
States Navy has assured me of more than one instance in which men had
fallen asleep under his own eyes, oppressed by exhaustion, during the roar
of a long continued bombardment. Thus produced, the relation of cause and
effect between weariness and sleep becomes very apparent. The refreshing
influence of such repose points clearly to the restorative character of
the physiological processes which persist during the suspension of
consciousness. It also renders evident the final cause of that periodical
interruption of activity which the brain experiences in common with every
other living structure.
Sleep is usually preceded for some time by a feeling of sleepiness. This
sensation, like the analogous sensations of hunger and thirst, represents
in some measure the progressive diminution of energy throughout the entire
body; but it is chiefly expressive of the failure of cerebral energy. It
produces a sense of general heaviness and intellectual dullness; the
special senses become less alert, the eyelids droop, numerous groups of
muscles experience the spasmodic contraction of yawning, the head drops
forward and is recovered with a jerk, the limbs relax, and the whole body
tends to assume a position convenient for repose. Every school-boy who has
been compelled to pass an evening hour at a dull lecture, under the eye of
a martinet monitor, will testify to the suffering which attends any
unusual prolongation of this period. But, if the natural course of events
be not obstructed, the stage of mere sleepiness is soon passed, and the
introductory stage of sleep is entered. This is a state in which the
individual is neither awake nor fully asleep. It is known as the
hypnagogic state. During this period the phenomena of simple sleepiness
become exaggerated to such a degree that the attitude of repose is assumed
without effort if the body be permitted to follow the natural inclination
of its different members. The eyes close, the other senses become
inactive, though the sense of hearing is the most persistent. Released in
considerable measure from the control of the brain, the reflex energy of
the spinal cord is at first somewhat exalted. Witness the fibrillary
twitching of the muscles, and the convulsive state, which may often be
observed during the stage of somnolence after severe fatigue. The uneasy
sleeper may even be roused to complete wakefulness by such involuntary
movements. But, as sleep becomes more profound, the reflex functions of
the cord are also weakened.[1] As the sensory organs retire from action,
the intellectual faculties lose their equilibrium. First, the power of
volition ceases. Then the logical association of ideas comes to an end.
The reasoning faculty disappears, and judgment is suspended. We become,
therefore, no longer capable of surprise or astonishment at the vagaries
of memory and of imagination, the only faculties that remain in action. To
their more or less unfettered activity we owe the presentation in
consciousness of those disorderly pictures which, occurring in this stage
of imperfect sleep, have been termed hypnagogic hallucinations.[2] During
the early moments of this period an observant person may often retain a
power of reasoning sufficient to remark the fact of dreaming, and this
effort of attention may produce a partial awakening; but, usually, the
subsidence of cerebral function is progressive and rapid. The fire of
imagination fades, the field of consciousness becomes less and less
vividly illuminated, the entire nervous apparatus yields to the advancing
tide, and, finally, the dominion of sleep is fully confirmed. The sleeper
knows nothing of the external world, and has lost all consciousness of his
own existence. But the duration of profound repose is brief. From the end
of the first hour the depth of sleep, at first, rapidly, then, more
gradually, subsides. Dreams disturb its tranquility, mental activity
increases, the power of volition revives, and, at the end of six or eight
hours, the individual is once more awake. The subjoined diagram, borrowed
from the Dictionaire Encyclopédique des Sciences Médicales, will
facilitate the apprehension of these successive phases in the course of
sleep:
+============================================================+
| Organic Life. |
| | Conscious Life. |
| | | Imaginative Faculties. |
| | | | Coördinative Faculties. |
| | | | | Special Sensation and Voluntary Motion.|
|----+----+----+----+----+-----------------------------------|
|XXXXXXXXXXXXXXXXXXXXXX | Normal life. |
|------------------------------------------------------------|
|XXXXXXXXXXXXXXXXX |First stage of sleep--Hypnagogic |
| | hallucinations. |
|------------------------------------------------------------|
|XXXXXXXXXXXX |Second stage of sleep--Dreaming. |
|------------------------------------------------------------|
|XXXXXXX |Third stage of sleep. |
|------------------------------------------------------------|
|XX |Profound sleep. |
|------------------------------------------------------------|
|XXXXXXX |First stage of waking. |
|------------------------------------------------------------|
|XXXXXXXXXXXX |Second stage of waking--Dreams. |
|------------------------------------------------------------|
|XXXXXXXXXXXXXXXXX |Third stage of waking--Hypnagogic |
| | hallucinations. |
|------------------------------------------------------------|
|XXXXXXXXXXXXXXXXXXXXXX |Complete awakening. |
+------------------------------------------------------------+
It was formerly believed that during the time of sleep all the processes
of assimilation and nutrition throughout the body are increased,--in
short, that it is the season of repair for the waste of tissue incurred
during the hours of wakeful activity. While it is true that in sleep the
expenditure of force is greatly reduced, the more exact researches of
modern physiologists indicate a universal reduction in the rate of all the
vital processes. The final result, however, is a general renewal of
energy, because the aggregate income of the tissues is greater than their
outgo during the suspension of conscious activity. The following
observations make very apparent the fact of a reduction of physiological
activity:
_Respiration._--The process of breathing is conducted with greater
deliberation during the period of sleep. This reduction is one of the most
notable of the circumstances that first attract the attention of the
spectator who observes a sleeping person. The average number of
respirations per minute, in an adult of twenty-five to thirty years of
age, is sixteen. Quetelet remarked[3] that during sleep this number was
diminished by about one-fourth. The same fact has been recorded by other
observers.[4] Mosso has also noted the fact[5] that there is a change in
the type of respiration, the movements during sleep become less
diaphragmatic and more largely costal. He furthermore observed that during
the waking period the act of inspiration consumed 8-12 of the complete
respiratory phase, but during sleep it was prolonged till it occupied
10-12 of the same cycle. The interval between the end of expiration and
the commencement of inspiration was also obliterated by sleep.
Notwithstanding this relative increase of inspiratory motion, the quantity
of air that passes through the lungs is considerably reduced by reason of
the diminished action of the diaphragm. A corresponding reduction of the
gaseous exchanges between the blood and the external air has been
determined by the experiments of Pettenkofer and Voit, Boussingault,
Lewin, and other equally competent observers.[6]
_Circulation._--During sleep the heart beats less frequently than during
the waking hours. Though a portion of this delay must be attributed to the
recumbent position, sleep does still further retard the movement of the
heart. My own observations upon children in bed exhibit a difference of
twelve to sixteen beats between the pulsations when awake and asleep.
According to Trousseau[7] the average number of pulsations observed in a
group of thirty children, varying in age from fifteen days to six months,
was 140 when awake and 121 when asleep. In another group of twenty-nine
children, between the ages of six months and twenty-one months, the
average was 128 when awake and 112 when asleep. The observations of Hohl
and Allix[8] indicate that among very young children the difference
between the pulse of sleep and the pulse of wakefulness may equal forty
beats. According to Guy (_loc. cit._) the pulse is more variable in the
morning than during the afternoon or evening.
_Temperature._--Aside from the almost hourly fluctuations of the bodily
temperature, a noticeable sinking of the temperature-curve is observed
during the hours of sleep. This alone is sufficient to indicate a
diminished rate of combustion in the tissues. Boussingault found[9] that a
dove which consumed 255 millegrammes of carbon every hour while awake,
oxidized only 162 millegrammes when asleep. Scharling also observed that
the quantities of carbon successively oxidized by the same man when asleep
and awake bore to each other the ratio of 1:1.237. The observations of
Demme[10] indicate that increase of bodily temperature during the hours of
sleep must be considered as the result of pathological processes in the
tissues. The observations of Allix (_loc. cit._), made upon sixteen
children during the first twelve days after birth, showed an average fall
of 0°.38 C. during the hours of sleep. Eight children, between five and
sixteen months old, exhibited a similar depression of 0°.56 C.; while ten
children, ranging in age from twenty months to four years of age, averaged
0°.34 C. less when asleep than when awake.
The well-known experiments of Chossat, who found that the temperature of
pigeons was from 0°.70 C. to 0°.90 C. higher at noon than at midnight, may
not be considered satisfactory evidence of the depressing influence of
sleep, because it is true that the diurnal variations of temperature which
are conditioned by the vital activities of every animal might be
sufficient to account for these differences. The experiments of
Horvath[11] are more convincing. This observer found that the marmots upon
which he experimented were accustomed to sleep during the winter for about
four days continuously, and would then remain awake for an equal length of
time. “During the sleeping period they can be cooled down to such a degree
that a thermometer introduced into the rectum to the depth of an inch and
a half indicated only 3°F. above the freezing point. The temperature rose
rapidly after the animal awoke, so that in the course of an hour it was
3°F. higher; at the close of the second hour 9°F. higher, and at the end
of the next half hour about 27°F. * * Neither respiration nor the muscular
movements were correspondingly augmented.” This observation clearly shows
the powerful influence of cerebral activity upon the liberation of heat
within the body.
_Secretion._--The functions of the numerous glands throughout the body are
diminished during sleep. The tears dry up, and the cornea receives less
moisture. Hence the stickiness of the margins of the eyelids during the
sleep of a patient suffering with conjunctivitis. He can open his eyes, on
awaking, only after sufficient time has elapsed to revive the lachrymal
flow. Exner[12] remarks the diminution of pathological secretion in nasal
catarrh during the hours of sleep. The mouth in like manner ceases to
receive its full quota of saliva, and its cavity quickly dries if the lips
remain open. The secretions of the gastro-intestinal glands vary with the
contents of the alimentary canal; but in general they are considerably
diminished, and digestion is correspondingly retarded during the hours of
sleep. The quantity of urine is lessened during sleep.[13] The elimination
of urea and of other excrementitious matters is less during the night than
by day.[14] Unless increased by disease, or by accidental circumstances
connected with atmospheric temperature and unnecessary clothing, the
perspiration is also diminished.
_Nutrition._--All the molecular processes of nutrition are reduced by
sleep. The lowering of the bodily temperature has been already indicated.
The observations of Helmholtz[15] indicate that the actual liberation of
heat in the tissues is but little more than one-third of the amount set
free in an equal period of time during the waking hours. The numerous
experiments[16] of Boussingault, Henneberg, Scharling, E. Smith,
Liebermeister, Pettenkofer, Voit, and Lewin, clearly indicate the fact
that during sleep less oxygen is absorbed, and less carbonic acid gas is
discharged, by the tissues. Voit found that while, during the daytime, 435
grammes of oxygen were taken in by a working man, only 326 grammes were
needed by the same individual during the nocturnal half of the day.
Artificial sleep occasioned by chloral hydrate produced a similar
reduction in the consumption of oxygen and in the formation of carbonic
acid gas. Under the influence of morphine the reduction of CO_{2.} reached
27 per cent., and the diminution of oxygen amounted to 34 per cent. of the
quantities furnished during wakeful activity. The comparatively small
reduction (only 6 per cent.) in the decomposition of the nitrogenous
elements of the body during the same period, exhibits the close relation
between the metamorphosis of the non-nitrogenous elements of the tissues
and the amount of bodily activity.
The experiments of Pettenkofer and Voit, to which allusion has just been
made, serve also to illustrate the fact that all tissue changes are
increased by every excitement of the sensory organs of the body, but are
diminished by the subsidence of peripheral irritations. Hence the
importance of quiet and darkness when we seek to induce that state of the
body in which molecular processes should reach their minimum. Since every
act of perception is attended by an outburst of refuse matter from the
nervous tissue, the quantity of such excrementitious discharge in any
given period of time becomes in some sort a measure of the vital activity
of the organism. Conclusive proof of the diminution of vital function
during sleep is thus obtained.
It must not, however, be inferred that the general reduction of
tissue-change, which has thus been established, during the hours of sleep,
is evidence of a universal and uniform reduction of function throughout
the body. Sleep seldom falls at once with equal force upon every organ;
its invasion is progressive. Consequently, certain structures may be fast
asleep, while others are partly awake,--while still other portions of the
organism may be in a condition of activity greatly in excess of their
ordinary wakeful function. Upon this fact depend the phenomena of dreams
and the various forms of somnambulism. The special senses are usually
overcome by sleep before the muscular apparatus yields, and the
cerebro-spinal nervous centres are the last of all to succumb. The eyes,
for example, cease to see clearly before the eyelids droop, or the muscles
of the neck give way in the act of nodding. The senses of touch and of
taste fail next in order, as in the case of the infant gourmand, who may
be seen falling asleep at supper,--his mouth yet filled with untasted
sweets from the table before him. The sense of smell is more persistent,
and its exercise is sometimes an obstacle to the invasion of sleep.
Witness the effect of powerful odors upon certain persons. The perfume of
flowering plants in the sleeping chamber is sometimes decidedly annoying
on this account. A lady of my acquaintance was once awakened out of a
sound sleep by the smell of tobacco smoke from the pipe of a thoughtless
burglar who had quietly entered a distant apartment of the house. A sudden
change of wind, deluging a city with the vapors of a glue-factory or
rendering establishment, may in like manner disturb the slumbers of
thousands of people.
The sense of hearing seems to be the most persistent of all the special
senses. It is not a very uncommon thing for persons to be awakened by the
sound of their own snoring; or, if not actually aroused by the noise, to
remain in a condition of repose which seems to be sustained and cheered by
the regular rhythm of its own music. As a general rule, however, it is
noteworthy that, when not wholly dormant, each sense finds its sphere of
activity greatly narrowed by the fact of sleep. Consequently the range of
perception, if not wholly obliterated, is greatly limited during the time
of sleep.
While it is true that sleep arrests the voluntary activities of the
muscles, it is also a fact that all the muscles do not yield at once or in
equal degree. The extensors of the neck, and the supporters of the spinal
column, are the first to fail. The patient begins to nod, and is inclined
to fall forward, before consciousness ceases. The muscles of respiration
and of circulation continue to contract, though at a diminished rate. The
vermicular movements of the intestinal coats persist, and in certain
conditions of ill-health their exaggerated contractions may become a cause
of imperfect repose. Reflex movements may always be excited during natural
sleep. Tickling the sole of the foot will cause retraction of the limb;
and before the complete establishment of sleep, a certain exaltation of
the spinal reflexes may be observed. Young children may frequently be seen
in the act of suction with their lips, as if at the breast; and the smile
of the sleeping infant is a matter of daily remark in every nursery. The
influence of dreams as an excitant of muscular movement will be hereafter
discussed.
The variation of intellectual function which appears in sleep serves to
measure its profundity and to indicate the extent of its invasion. The act
of perception being dependent upon sensation, it is to be observed that
the range of perception diminishes so soon as the organs of sense begin
to yield. Its intensity may not immediately fail, but the breadth of its
scope is narrowed. Sometimes, however, the act of conscious perception is
arrested before the organs of sense are sealed. The sleepy reader may
continue to eye the page before him, perhaps even to read aloud for a
considerable time after he has ceased to derive any meaning from the words
of the book. In such cases the organs of perception and conception and
association of ideas slumber before the bonds of connection between the
will and the muscular organs have been completely relaxed. Such an example
affords a valuable illustration of the division of the brain into separate
mechanisms which, though most intimately related, are nevertheless
partially independent of each other. Sleep may operate like an invasive
disease, falling with unequal incidence upon the different structures that
make up the mass of the brain, paralyzing one portion, while simply
benumbing another, and even arousing to excessive activity a third.
Consequently the intellectual functions may be very unequally disturbed,
and the order of their subsidence may be considerably varied; but, as a
general rule, the physiological relations of the faculties are respected,
so that as sensation diminishes, perception fails, the conception of ideas
is correspondingly hindered, and the association of such ideas as are
still projected upon the field of consciousness becomes more imperfect.
The loss of the power of association implies the destruction of memory and
the impossibility of exercising the reasoning faculty or of forming those
judgments upon which every act of volition is based. When the brain has
at length been so far overwhelmed that physical impressions can no longer
reach the field of consciousness, all manifestation of intellectual life
is at an end, and the sleeper sleeps a dreamless sleep that leaves no
trace behind.
It is assumed in the last sentence that the brain may become so far
transformed by sleep that it ceases for the time to be capable of function
as the instrument of thought. This conclusion has been questioned by the
very highest authorities. Sir William Hamilton, Exner, and many others
have instituted numerous experiments to test the possibility of a
dreamless sleep. Causing themselves to be suddenly aroused at all hours of
the night, they invariably found themselves at the instant of awaking
occupied with the course of a dream. Hence it has been inferred that the
mind is always alert, even when the body is most thoroughly asleep. In
explanation of the fact that consciousness contains after deep sleep no
trace of such mental activity, it is claimed that the act of dreaming of
which we are aware at the moment of waking is proof of intellectual
function during the moments which preceded that incident, and that we are
merely forgetful of all similar processes that occurred during undisturbed
sleep. The unconsciousness of sleep, according to this theory, is not
real--it is only apparent through failure of the memory. If this be true,
memory is the only intellectual faculty of whose inaction we can be sure.
The period of deep sleep might then be, for all we know to the contrary, a
period of the most intense and exalted mental activity. But, if so, it is
quite worthless as a constituent of our conscious existence. It may also
be objected with equal reason that the dreams which unquestionably occupy
the field of consciousness at the instant of waking are probably excited
by the impressions which terminate sleep. The process of waking, though
often very greatly hurried, is by no means absolutely instantaneous. As we
shall learn, the time requisite for the evolution of a dream may be
indefinitely brief. Consequently, it seems better in all such instances to
assign the period of dreaming to the time of diminishing slumber that
corresponds to the disturbance by which sleep was terminated.
The only reason for any hesitation in the acceptance of such a proposition
consists in the reluctance of many philosophers to admit the possibility
of any interruption in the active life of a spiritual being, such as man
is conceived to be. But it is difficult to comprehend any valid reason for
the denial of such interruption. Every form of force, of which we have any
knowledge, is subject to fluctuations in the course of its phenomenal
manifestation. When a physical force ceases to exhibit itself in an active
state, and passes into a potential modification, we are not compelled to
regard it as extinguished. It is merely latent or inhibited, but always
ready to take its place again among the kinetic forces of nature. In like
manner there seems to be no good reason why that spiritual force or
congeries of forces which constitutes the mind of man may not experience
analogous transformations in successive periods of action and of repose.
Such periods of rest occur in sleep, in coma, in disease and
disorganization of the brain. The mind sleeps, it does not cease to
exist--probably not even when death dissolves its material substratum.
That the depth of sleep is exceedingly variable is evident in the
experience of every one. A German physiologist[17] has made a rough
estimate of the soundness of sleep by comparing the loudness of the noises
necessary to wake the subject of experiment at regular intervals during
the course of the night. He arranged a gong with a pendulum attachment,
and noted the length of the stroke which produced a sound sufficiently
loud to awaken the patient. In this way the different degrees of intensity
of the awakening noise could be calculated, and the corresponding depth of
sleep could be estimated. It was thus concluded that the depth of sleep
increases rapidly during the first hour, at the end of which time it has
reached its maximum. During the next half hour it diminishes as rapidly as
it had increased in the first half hour. During the next hour it still
further diminishes, almost as much as it increased during the second half
hour. The remaining ten half hours of the experiment were occupied by a
comparatively light and gradually diminishing slumber, until the vanishing
point of sleep was reached at the expiration of eight hours from its
commencement. This observation corresponds with the general opinion that
sleep is deepest in the early part of the night. For the same reason
dreams and wakefulness are most frequent during the early watches of the
morning.
When considering the causes of sleep it is needful to exclude from view
those artificial varieties of sleep that are produced by the various
narcotic drugs, as well as the counterfeits of sleep which result from
diseased conditions of the body. It is comparatively easy to frame
hypotheses in explanation of such interruptions of our conscious life;
but, when we attempt to formulate a theory which shall satisfactorily
account for the occurrence of natural sleep in healthy animals, the task
becomes exceedingly difficult.
First among the causes of sleep may be reckoned the alternation of day and
night. With the disappearance of sunlight all nature sinks into a
condition of repose.
“The night brings sleep
To the greenwoods deep,
To the bird of the woods its nest;
To care soft hours,
To life new powers,
To the sick and the weary--rest!”
In this tendency to nightly inaction man shares with all other living
creatures. His body thus testifies to the intimacy of its relations with
all portions of the solar system. Originated in the tropical regions of
the earth, where day and night are nearly equal, we find in all parts of
the world the same hereditary need of a period of rest, nearly coincident
with the duration of the shorter nights of the tropical year. Had the
birth-place of primeval man been situated within the Arctic circle, it is
probable that his hours of sleep might have differed considerably from
the number now needed by the average individual. So powerful are the
necessities thus dependent upon the harmony between our organization and
the movements of the earth, that if the habit be formed of sleeping at
other hours than those which are usually devoted to that purpose, the full
complement of sleep is still needful to satisfy the demand for rest.
Prominent among the causes which predispose to sleep at night is the
cessation of a majority of the sensations that are continually pouring in
upon the brain during the period of daylight. Hence the necessity for
seclusion in darkened rooms, from which the noises of the daytime are shut
out, if one would sleep during the long days of the arctic summer, or if
one would enjoy a midday nap at any season of the year. The close
dependence of wakefulness upon the constant activity of the organs of
sensation, is well illustrated by a case related in Hermann’s _Handbuch
der Physiologie_, Vol. II, Part 2, p. 295. A young man had been reduced by
disease to such a condition of general anæsthesia that the right eye and
the left ear were the only remaining paths of sensation between his brain
and the external world. Whenever the sound eye and ear were bandaged so as
to cut off all communication with the brain, the patient invariably fell
asleep in the course of two or three minutes after the interruption of
sensation. In like manner, some people, even in perfect health, are able
to sleep at any time by simply lying down and closing the eyes. Such
persons, however, are not often very highly gifted in the intellectual
sphere. They generally belong to a class of men whose lives are laborious
and liable to great irregularity and fatigue. Such people labor in the
open air, where every organ of sense is in a state of continual
excitement. As soon, therefore, as they can find a quiet corner from which
the commotion of the elements is excluded, it is only necessary to close
the eyes--the principal avenue of communication with the outside
world--and sleep begins at once. This is especially true if severe bodily
exertion has preceded the opportunity for repose.
Fatigue of any sort is one of the most energetic causes of sleep. The
impossibility of long sustained exertion is a fact almost too familiar to
attract attention. Every muscle must be suffered to rest for a time after
contraction before it can be again contracted. Even the heart and the
muscles of respiration must be allowed to enjoy regular periods of repose
many times each minute. These are examples of local rest, not involving
the entire body. But if the whole body participate in any violent action,
every part will manifest a consequent disposition to rest. Witness the
effects of the venereal act. Every muscle is relaxed; the brain, which has
officiated as the supreme source of energy, experiences exhaustion, and
sleep frequently terminates the voluptuous paroxysm. In like manner,
sensations of severe pain, if sufficiently prolonged, become a cause of
sleep. Prisoners upon the rack have slept through sheer exhaustion while
undergoing the horrors of torture. Little children frequently fall into a
deep sleep immediately after painful, though comparatively bloodless,
surgical operations performed without anæsthetics. The depressing
emotions, even, may so fatigue the brain as to induce sound sleep through
reaction from previous excitement. Every wearied portion of the body must
rest; and when the brain thus rests, sleep is the consequence.
Impressed by the force of such considerations, certain physiologists[18]
have reasoned from the analogies suggested by a study of the results of
muscular fatigue, and have suggested an hypothesis accounting for the
occurrence of sleep by a supposed loading of the cerebral tissues with the
acid products of their own disassimilation during wakeful activity. The
acid reaction of the brain and of the nerves after exertion, corresponding
with the development of acids in the muscular tissues during contraction,
suggested the probability that an excessive presence of lactic acid and
its sodic compounds might be the real cause of cerebral torpor and sleep.
Could this hypothesis be proved, ordinary sleep would take its place along
with the states of unconsciousness induced by anæsthetics and hypnotics,
and the lactate of sodium should be found the very best of medicines for
the relief of wakefulness. Its administration for this purpose, however,
has yielded only the most discordant and unsatisfactory results. The
fatigue theory, moreover, is insufficient, since it furnishes no
explanation of the invincible stupefaction produced by cold, nor does it
render intelligible the unbroken sleep of the unborn child.
Far more comprehensive is the hypothesis advanced by Pflüger.[19]
According to this view, the state of wakefulness is maintained by a
certain degree of activity in the cortical substance of the brain. Like
all other bodily organs, this substance is renovated by the assimilation
of nutrient materials derived from the blood. By this process oxygen is
stored up in chemical combination, forming “explosive compounds,” whose
precise composition is not fully understood. When for any reason the
supply of oxygen is insufficient, as in hemorrhage, producing cerebral
anæmia, or in impregnation of the red blood corpuscles with carbonic oxide
or chloroform, or other substances capable of excluding oxygen from the
hemoglobin of the corpuscle, the cerebral tissues are imperfectly
renovated. The explosive constituents of the cortical protoplasm are then
inadequately renewed after mental activity, and the sensitive portions of
the brain are no longer fitted to manifest the highest forms of
intelligent activity. But, when nothing interferes with healthy nutrition,
the requisite degree of instability in the protoplasm of the brain is
effected by intussusception of oxygen. Under the influence of the various
nervous impressions which reach the brain, the unstable protoplasmic
compounds break up into simpler forms. The motion thus liberated by these
“explosions” of excitable matter is, in some way at present utterly
inconceivable, projected upon the field of consciousness where the mind
dwells; and we are thus brought into conscious relation with the external
world.
That the capacity for thus signalling across the gulf which divides
matter from mind is the result of a certain perfection and complexity of
physical structure is rendered probable by the utter failure of the
infra-cortical organs alone to impress the conscious intelligence by any
amount of independent activity. The same thing is also indicated by the
unconscious sleep of the rudimentary fœtal brain, and by the brevity of
the intervals of wakefulness which mark the life of the new born babe.
That this capacity is dependent upon a special mobility of the atoms of
the brain, is shown by the speedy cessation of intelligence which follows
great reduction of temperature, as in hibernation, or during exposure to
severe frost. That its exercise is largely dependent upon the activity of
the senses is proved by interference with their function, as in the case
above quoted (see p. 18) from the observations of Strümpell.
The dependence of the waking state upon the presence and activity of a
sufficient quantity of a peculiarly unstable form of protoplasm in the
brain is an hypothesis which presents no great difficulty of
comprehension. But how may we explain the lapse from the intelligent
vivacity of that waking state into the unconscious inactivity of sleep? I
have elsewhere[20] discussed the manner in which artificial sleep is
produced by impregnation of the brain with anæsthetic substances that
interfere with sensibility, and finally produce stupefaction, by hindering
the normal processes of intra-molecular oxidation in the protoplasm of the
nervous tissues. The same general line of argument may be extended to
cover the action of every narcotic agent with which the living substance
of the body may become surcharged. Accepting, then, the hypothesis
advocated by Obersteiner and Preyer, it becomes an easy thing to account
for the gradual onset of sleep by supposing an accumulation of the
“fatigue producing” products of intra-molecular oxidation. But we cannot
thus explain the rapid and, as it were, voluntary passage from wide
awakefulness into a condition of deep sleep, such as may be commonly
observed among sailors and others who have formed the habit of going at
once to sleep at regularly recurring hours of the day or night. Certain
writers have endeavored to account for this fact by imagining a special
mechanism at the base of the brain (choroid plexuses of the fourth
ventricle, etc.,) by means of which the current of the blood through the
brain may be voluntarily diminished, with a consequent arrest of conscious
activity. But, still adhering to the hypothesis of Pflüger, we shall
obtain a clearer explanation of the facts by considering the phenomena
connected with the succession of impressions upon the organs of sense. It
has been ascertained[21] that such impressions must persist for a certain
measurable length of time in order to excite conscious perception. A sound
must be prolonged for at least fourteen-hundredths of a second, a ray of
light must agitate the retina for about eighteen to twenty-hundredths of a
second, an ordinary contact with the surface of the skin must continue
from thirteen to eighteen-hundredths of a second, in order to awaken any
knowledge of sound and light and tactile sensation. For the simplest act
of perception from two to four-hundredths of a second are necessary. It
is, therefore, perfectly reasonable to suppose that when the “explosive
material” of the brain has been sufficiently “dampened” by the
accumulation of acid refuse which accompanies prolonged cerebral effort,
the impressions of sense may no longer suffice to excite in the cortical
protoplasm vibrations of sufficient length, or following each other in
sufficiently rapid succession, to sustain consciousness. The cortex of the
brain may then be likened to a body of water into which bubbles of
partially soluble gas are introduced from below. When the bubbles are
large, and when they follow each other rapidly, a continual effervescence
is maintained upon the surface of the water. But if the size of the
bubbles be reduced, or if the solvent capacity of the liquid be increased,
the surface will become almost, if not quite, perfectly tranquil. In some
such way, without any great danger of error, may we picture forth the
manner in which the generation of ideas in the field of consciousness is
related to the molecular movements in the space occupied by the
protoplasmic substance of the brain. Returning, now, to the rapid
induction of sleep, we find that it is usually the experience of people
who lead an active life in the open air, and are compelled to endure
frequent interruption of their rest. The sailor who is trained to work
four hours on deck, and then to sleep four hours below, has been virtually
transformed by this habit into a denizen of a planet where the days and
the nights are each but four hours long. His bodily functions become
accommodated to this condition; his nervous organs store up in sleep a
supply of oxygenated protoplasm sufficient only for an active period of
four or five hours; so that, when the watch on deck is ended, he is in a
state as well qualified for sleep as a laborer on shore at the close of a
day of twelve or fifteen hours. Moreover, the majority of those who can
thus easily fall asleep are individuals whose waking life is almost
entirely sustained by external impressions. So soon, therefore, as such
excitants are shut out by closing the eyes in a place of shelter from the
sounds and turmoil of the air, comparatively little remains for the
stimulation of ordinary consciousness, and sleep readily supervenes
through mere lack of cerebral excitement, especially if the excitable
matter of the brain has been previously overwhelmed by the products of
active exertion.
That analogous, though not identical, predisposition to unconsciousness
may also be rapidly induced by modifications of the cerebral circulation
is proved by the sudden reduction of cerebral excitability and
consciousness which occurs during the act of fainting. In this counterfeit
presentment of sleep the important part played by variations of the blood
current through the brain is so conspicuous that certain writers have
attempted to show that genuine sleep is the result of a diminution in the
flow of blood to the cortex of the brain. An ingenious physician has even
attempted to relieve insomnia very much as a surgeon might undertake to
cure a popliteal aneurism--by placing tourniquets on the arteries leading
to the affected part. But the mere fact that syncope produces
unconsciousness does not prove that “cerebral anæmia” should be elevated
to the rank of the principal cause of natural sleep. The nervous process
is the primary factor. The circulation of the blood is everywhere under
the immediate control of the nervous system. Consequently, every change in
the condition of the nervous structures is followed by a corresponding
change in the state of the circulating apparatus. Wherever an organ is
aroused to activity, so delicate are the adjustments by which it is
connected with the brain and with the heart that it is at once irrigated
by an increased flow of blood. When its functional activity subsides, the
same mechanism provides for a corresponding reduction in the supply of
blood to its tissues. The brain itself forms no exception to this law.
This has been admirably shown by the observations of Professor Mosso, of
Turin.[22] The learned professor enjoyed the rare opportunity of observing
three individuals who had suffered the loss of a considerable portion of
the bony walls of the cranium, exposing the surface of the cerebrum, and
affording a view of the pulsation of the vessels of the brain. With the
aid of the cardiograph, the sphygmograph, the hydrosphygmograph, and the
plethosphygmograph, it became possible to register the circulation of the
blood in the brain, and to compare that portion of its course with the
coincident circulation in other parts of the body. It was thus shown that
every increase of emotional or intellectual activity was attended by an
increase in the activity of the cerebral circulation. This increase was
procured at the expense of other portions of the body, which exhibited a
coincident reduction in the amount of blood received from the heart. The
occurrence of sleep caused a diminution in the number of respirations,
and a fall of six or eight beats in the pulse. The volume of the brain and
its temperature were at the same time slightly reduced, through the
diversion of blood from the head to other regions of the body. The
consequent dilatation of the vessels in the extremities was readily
demonstrated by the use of the plethosphygmograph. The extreme
sensitiveness of the nervous centers was further illustrated by the fact
that if, during sleep, a ray of light were directed upon the eyelids, or
if any organ of sense were moderately excited without waking the patient,
his respiration was at once accelerated; the heart began to beat more
rapidly, the vessels of the extremities contracted, and the blood flowed
more freely into the brain. Similar results accompanied the act of
dreaming. The return of full consciousness on waking was followed by an
immediate increase in the activity of the intra-cranial circulation.
The extreme susceptibility of the brain to influences proceeding from
artificial disturbances in the circulation, was exhibited in the case of
one of Professor Mosso’s patients. By compression of the carotid arteries,
unconsciousness was induced, and an attack of convulsions was aroused. In
no other part of the body can a corresponding disturbance of function be
so quickly produced by similar means. A limb may be rendered bloodless for
nearly half an hour, by the application of an elastic bandage, and yet its
sensory nerves will remain capable of transmitting impressions from the
periphery. But in this case, compression of the carotids for only eight
seconds was sufficient to abolish consciousness and to excite convulsive
movements.
In all such observations it is worthy of note that the nervous impression
is the primary event so long as artificial disturbances are not intruded.
The changes of blood-pressure and circulation were invariably secondary to
the excitement of nerve tissue. Sleep, therefore, must be regarded as the
cause, rather than the consequence, of the so-called cerebral anæmia which
obtains in the substance of the brain during repose. This condition of
“anæmia” is nothing more than the relatively lower state of circulation
which may be remarked in every organ of the body during periods of
inactivity. Every impression upon the sensory structures of the brain
occasions a corresponding liberation of motion in those structures. The
movement thus initiated arouses the vaso-dilator nerves of the cerebral
vessels and excites the vaso-constrictor nerves of all other portions of
the vascular apparatus. Hence the superior vascularity of the brain so
long as the organs of sense are fresh and receptive. Hence the diminishing
and varying vascularity of the different departments of the brain as sleep
becomes more or less profound. These modifications of the brain and of its
circulation are well illustrated by the effects of a moderate degree of
cold applied to the cutaneous nerves of the body, as not unfrequently
happens when the night grows cool towards morning. The disturbance of the
sensitive nerves of the skin is transmitted to the brain. The excitement
of this organ causes dilatation of its vessels, and increased irritability
of the cortical instrument of perception. This becomes the starting point
for the projection of impulses upon the field of consciousness, producing
dreams, or even a complete awakening from sleep.
The cause of sleep must, therefore, be sought in the molecular structure
of the brain, rather than in fluctuations of the blood-current. In the
present state of our knowledge it must be negatively represented as the
consequence of a deficiency in the amount of movable oxygen in the nervous
tissue. This deficiency may be the result of immaturity, as in the fœtus,
or in the new-born infant; or it may result from the accumulation of an
excess of the waste-products of intra-molecular oxidation during
functional activity--products which hinder the further passage of oxygen
into stable combination with the oxidizable elements of protoplasm. Sleep
thus produced differs from the artificial sleep induced by narcotic drugs,
in the fact that its cause is self-generated by the instrument of thought,
while narcotic stupor is caused by the intrusion of substances derived
from without--substances which, like the natural refuse of the living
cells, more or less completely hinder the processes of oxygenation and
oxidation within the tissues of the body. Hence the states of healthy
sleeping and waking must necessarily be self-limited and regularly
successive; while the state of narcotism is purely accidental, and its
duration exactly corresponds with the variable length of the period during
which the body may remain impregnated with the hypnotic agent.
Certain morbid forms of sleep further illustrate its dependence upon the
persistence of depression in the functional activity of the brain. For
some persons this seems to constitute their normal condition. They are
either excessively fat, red-faced, and soaked with beer, or they are pale,
anæmic, and pulpy, with flabby muscles and a feeble circulation. They fall
asleep whenever left to themselves, and never seem to be fully aroused to
active life. The fat boy who figures so amusingly in The Pickwick Papers,
furnishes a life-like picture of this variety of _somnolence_.
The introductory stage of the eruptive fevers is often characterized by
somnolence. It also frequently appears as the forerunner of coma in the
various diseases which terminate in unconsciousness and death. A singular
example of this has been observed among the negro inhabitants of the
Atlantic coast of tropical Africa. The disorder is known to English
writers as _sleeping dropsy_; by the French it is called _maladie du
sommeil_. It is characterized by daily paroxysms of somnolence which tend
to become more and more continuous and profound until they are finally
merged in fatal coma. For our knowledge of the disease we are chiefly
indebted to the description by Clark,[23] an English surgeon who practised
in Sierra Leone, and to the monograph by Guerin,[24] a French naval
surgeon, who had enjoyed exceptional opportunities for observation among
the laborers who had been carried from Africa to the island of Martinique.
Similar cases have been occasionally reported in other regions of the
world, but it is among the Africans that it has been principally remarked.
The onset of the malady is gradual, commencing with a slight frontal
headache. After a few days a disposition to sleep after meals is noted.
This becomes increasingly urgent, and the intervals of sleep are prolonged
until at length the patient becomes continually soperose. The waking
periods are marked by a sluggish state of the intellectual faculties. The
pulse is not accelerated, and it remains full and soft. The veins of the
sclerotic are turgid, and the eyeball seems unusually prominent. The
temperature does not increase, but rather tends to diminish its figure.
The skin is dry and moderately cool. The tongue continues moist, and is
covered with a white fur. The bowels and the bladder are regularly
emptied, and the appetite persists with considerable vigor. Finally, the
patient becomes completely comatose, and dies quietly. Sometimes, however,
the evolution of the disease is less tranquil. Epileptiform convulsions,
followed by progressively deepening periods of coma, interrupt its course,
and a continuous muscular agitation marks the closing scene. At the same
time the pulse grows weaker and more frequent until its movements cease in
death. Recovery is almost unknown, though the duration of the disease
often varies from three months to a year or longer. Examination of the
body after death yields very negative results; the sinuses and larger
vessels of the brain are engorged with blood, but no evidence of
inflammation is anywhere apparent. The other organs present no
pathological alterations whatever. These observations seem to indicate
that the disease originates in some form of general blood-poisoning,
rather than in any local inflammation or degeneration. Dr. Clark has
called attention to an enlargement of the cervical glands as a feature of
the malady. According to Dr. G. H. Bachelder,[25] the native physicians
cure the disease by extirpation of the affected glands. He has also
observed an initial lesion in the nasal mucous membrane. If this be
confirmed, the malady will take its place among the forms of somnolence
produced by infection of the blood.
Between the profound unconsciousness of natural sleep and _coma_ may be
placed the distinction that the one is always the consequence of healthy
physiological processes, while the other is always the result either of
injury, of disease, or of some form of intoxication. Comatose
unconsciousness may be the result of cerebral compression caused by injury
of the head, or by the presence of an inflammatory exudation.
Intra-cranial tumors, embolisms, thrombi, diseases of the cerebral
arteries, and degenerations of the brain,--in short, every morbid change
of which the liquids and the solids within the cranium are capable--may
become the cause of coma. Toxæmic conditions of the circulating fluids of
the body may benumb the brain with comatose sleep. Few diseases,
therefore, exist without the possibility of coma as one of their
consequences--a coma which, however, must not be confounded with the
genuine sleep which sometimes occupies the larger part of convalescence
from acute illness. During such convalescence there is a reversion to the
infantile type of nutrition with all its need of prolonged and frequent
periods of repose. Like normal sleep, the comatose condition admits
considerable variation of intensity. The patient may sometimes be
partially roused, as from the coma of alcoholic intoxication, and he may
finally recover complete consciousness; but very often the reverse is the
fact. The coma deepens into paralysis of the respiratory centres, and
death concludes existence without the slightest manifestation of
sensibility or intelligence.
_Lethargy_ is a pathological variety of sleep, in which the repose of the
body is even more complete than in coma. The victim of coma often presents
a countenance suffused with blood; the pulse beats vigorously, and
respiration may become stertorous. But in lethargy the abolition of bodily
movement is almost absolute. In the milder forms of this disorder the
patient may be partially roused, so as to attempt an answer when
addressed, appearing like a person in very deep sleep; but in the majority
of cases he remains insensible, unconscious, and utterly irresponsive to
ordinary forms of irritation. Respiration and circulation are reduced to a
minimum, and may, even for a time, become imperceptible. Uncomplicated
with hysteria, the disorder is rapidly fatal, but, according to
Rosenthal,[26] hysterical lethargy is never mortal.
Many examples of this disease have been afforded by the records of
apparent death. I am well acquainted with a lady who, in early childhood,
had been laid out for burial at the supposed termination of some infantile
illness. Her mother alone insisted that the child was still alive. After
some time spent in weeping and expostulation, she applied a blister to the
thorax of the babe. This soon excited evidences of painful irritation,
followed by a complete recovery. Still more instructive is the case,
narrated by Rosenthal,[27] of a young woman, twenty-four years of age,
who, in consequence of violent emotional excitement, became unconscious,
and presented no signs of life, though tested by placing a mirror before
the mouth, and by dropping melted sealing-wax upon the skin. On raising
her eyelids, the pupils gave no reaction to light; the limbs remained
perfectly flaccid, and the radial arteries were pulseless. Careful
auscultation, however, detected a very feeble and intermittent sound in
the cardiac region. The walls of the chest exhibited no movement, but the
lateral surfaces of the abdomen presented a slow and almost imperceptible
oscillation. Gentle faradization of the muscles and nerves of the face,
arm, and hand, excited definite muscular contractions. By this method
Rosenthal became satisfied that, although the patient had remained for
thirty-two hours in this condition, she was only apparently dead. In fact,
after continuing forty-four hours in a state of suspended animation, she
awoke spontaneously, made a rapid recovery, and seemed to enjoy as
comfortable health as an excitable, nervous temperament would permit.
Certain authors make a distinction between lethargy and apparent death;
but the difference is one of degree rather than of kind. The movements of
respiration and of circulation, though greatly enfeebled, are readily
observed in ordinary forms of lethargy; but in apparent death the pulse
can no longer be discovered, and nothing more than the faintest sound can
be distinguished in the region of the heart. It, therefore, becomes
important to have within reach a crucial test of the persistence of
general vitality. Such evidence, according to Rosenthal, is furnished by
the faradaic current. Within two or three hours after actual death, the
muscles cease to respond to the induced current; but in apparent death
this form of electro-muscular contractility never disappears. Every other
test that has been proposed has failed under certain circumstances.
Observation of the changes in muscular temperature during electrical
excitation is a method better adapted to the laboratory than for clinical
practice.
_Lucid lethargy._--In certain cases of apparent death the patient exhibits
all the external appearance of suspended animation, but the power of
conscious perception does not cease. The senses of sight and hearing
remain, and are, perhaps, intensified by inhibition of the power of
voluntary movement. The sufferer sees and hears; perception, emotion,
memory, the power of reasoning, judgment, volition, all persist. Only the
power of executing voluntary movements is lacking.
The victims of this variety of apparent death are usually women, or men
who are characterized by a feminine nervous organization. Great mental
excitement, fatigue, semi-starvation, and exhausting diseases, are the
principal exciting causes of the event. The following case, related by my
friend, Dr. P. S. Hayes, of Chicago, illustrates the phenomena of lucid
lethargy. The patient was a female physician, about thirty years of age,
unmarried, and consumptively inclined. During the course of a long and
wearisome hospital service, she was prostrated with typhoid fever.
Placing herself under the immediate care of my informant, she was also
attended by several of the most eminent physicians in the city. After a
long and exhausting illness she appeared to be dying. In the presence of
her physician, and surrounded by her relatives, she ceased to breathe. The
pulse stopped, life seemed to have gone out. Bottles of hot water were
applied to the limbs, and various restoratives were employed. After a
considerable time she began again to breathe, and a gradual recovery
followed. During the whole time of apparent death, consciousness had been
preserved. She seemed to be looking down from a point above her bed; she
could see the doctor feeling for her pulse, and was grieved by the sorrow
of her friends. Ordinary sensation was temporarily suspended, and she
could not distinguish the contact of the hot-water bottles that were
applied to her limbs, though actually scalded by their excessive heat.
Borne upon the wings of an excited imagination, she thought herself
permitted to look into heaven, but was not suffered to enter its gates. In
this exaltation of the imagination the reasoning faculties also shared, so
that certain philosophical problems which had previously baffled her
intellect were now perfectly comprehensible, and the memory of their
solution persisted after recovery.
Many similar narratives have been duly authenticated, but the limits of
the present chapter will not permit a discussion which properly belongs to
an investigation of the phenomena of trance. The important fact for
present consideration is the persistence of conscious life, despite the
appearance of death. In this preservation of consciousness,
notwithstanding the temporary suspension of certain kinds of sensibility
and the power of voluntary motion, may be discovered a relationship
between the phenomena of lucid lethargy and various disturbances of sleep,
which will be considered in a succeeding chapter.