Insomnia; and Other Disorders of Sleep

by Henry M. Lyman

The harmonious activity of all parts of the nervous system is indispensable to the highest exercise of the conscious mind. Healthy intellectual life is the perfectly balanced outcome of the complex polygon of forces which has its seat within the brain. In the waking condition this “moving equilibrium,” as it has been happily termed,[57] is sustained by the convergent impulses which are continually entering the brain through the pathways afforded by the several senses. Our waking hours are occupied with the ideas and with the associated trains of thought which are thus projected upon the field of consciousness. As a consequence of the harmonious function of the organs of sense, each one supplementing and correcting the information furnished by the others, a continuous process of perception and logical thought is maintained. But, along with the procession of ideas which are clearly conceived by the mind, the field of consciousness is also invaded by a cloud of half formed perceptions, which are too imperfect and fleeting to occupy the attention. As in the act of vision, though the periphery of the visual field is crowded with a whole world of objects dimly perceived without challenging particular attention, only the center of that field furnishing clear images to the brain, so the eye of the mind comprehends only a few of the impressions which enter the sphere of consciousness. The swarm of unnoticed perceptions, however, is none the less the result of abiding sensory impressions graven in the substance of the brain, from which, through the action of memory, they may at any favorable moment reënter consciousness. Sleep does not wholly arrest this process. A certain amount of projection into the field of consciousness continues, even during profound repose; and the ideas thus aroused form the material of our dreams.

It has already been remarked that the invasion of sleep is not an instantaneous process. One by one the senses fall asleep, and long before the final cessation of their activity, sleepiness hinders their function. Hence a progressive narrowing of the range of external perception; hence a reduction of the vividness of impressions derived from the outside world; hence, also, a simplification of the actions and reactions which constitute the “polygon of forces” active within the brain. But the suppression of certain lines in this polygon does not suppress life, nor does it necessarily destroy consciousness. It only occasions a redistribution of force, and a proportionate narrowing of the stream of related ideas. Since this process of suppression, just mentioned, is not an absolute quantity, but a variable factor, the polygon of physical forces within the brain and the corresponding succession of ideas in consciousness must necessarily be in a state of continual change. Consequently, our dreams must be as variable as the clouds that drift upon the currents of the air. As, on a hot day in summer, when the equatorial draught has ceased to guide the wind, we may observe all manner of local tides among the masses of vapor which arise from the earth, so, in sleep, when the guiding influence of the senses is withdrawn, the ideas that still arise are chiefly dependent for their origin and association upon the automatic and endogenous activities of the brain. Undisturbed by impulses from the external world, the brain seems then to become more sensitive to impressions that have their origin within the body. An overloaded stomach, an enfeebled heart, a turgid sexual apparatus, or an irritable nervous ganglion, may become the source of irregular and uncompensated impulses which, without disturbing the organs of special sense, may invade the cerebral cortex, and may there set in motion a whole battery of mechanisms whose influence upon consciousness would remain quite unnoticed were the external senses in full operation.

Still another cause for the production of dreams is to be found in the more or less complete suspension of the power of volition which accompanies sleep. Every act of attention is the result of exercise of the will. But the perfect exercise of the will is dependent upon the perfect development and wakefulness of the brain. So soon as sleep begins to invade the brain, the will begins to lose its normal incitement to action, and finally it becomes almost wholly disconnected from the muscular organs. In this state the sleeper may desire to perform some act—he may wish to move his limbs or to cry out aloud, but he can move neither hand nor foot, he cannot utter a sound. In other instances a partial connection between the will and the locomotive organs persists, and various orderly movements can still be produced. In like manner the control of the will over the succession and association of ideas may be either wholly, or only partially, lost in sleep. The deeper the sleep the more complete the loss of such control; hence the greater incoherence as well as feebleness of impression which is characteristic of dreams when sleep is profound. The vivid and panoramic succession of visual conceptions which constitutes a “vision,” occurs during light and partial sleep, when the will is still capable of in some measure guiding the procession of ideas.

For a similar reason the higher faculty of judgment, and especially the power of arriving at moral conclusions, is in great measure suspended during sleep. Like the power of volition, the activity of the moral sense is dependent upon a certain functional perfection in the brain. When the capacity of the brain is depressed by drugs or by disease, or by sleep, the moral sensibilities are the first to disappear. Hence the non-moral character of the impressions usually experienced during the act of dreaming. We feel neither surprise nor regret at the incidents of ordinary dreams. It is only when the border line of wakefulness is reached that the dreamer feels ashamed of walking naked in his dream, or feels compunction for an act of crime, or experiences emotions of joy or sorrow in connection with the incidents of his vision.

A dream may, therefore, be defined as the occupation of the field of consciousness during sleep by a succession of ideas more or less completely withdrawn from the guidance of the senses and from the control of the will. A great variety of dreams may thus be admitted, ranging all the way from those products of mere absence of mind which constitute revery, down to the faintest and feeblest stirrings of consciousness which have been always observed during the act of waking from the profoundest sleep.

Considerable light may be thrown upon the production of dreams if we consider attentively the manner in which illusions and hallucinations are excited by the use of drugs or by disease during the waking state. When engaged in experimenting upon myself with different medicines, I once took a dose of hasheesh sufficient to produce the peculiar effects of the drug. Sitting quietly in my chair, the first unusual sensation was an agreeable feeling of coolness diffusing itself over the surface of the body, as if some one were gently fanning me on a hot day. A feeling of causeless amusement began to occupy my mind. I seemed to be smiling all over without any apparent reason for hilarity. Then the walls of the room in which I sat seemed to recede to a vast distance. My attention became riveted upon a little picture which hung against the wall before me. It was a sunset scene, painted upon a canvas scarcely larger than my hand. As the wall upon which it was placed seemed to recede, the canvas expanded until I beheld a glorious landscape bounded by a range of snow-capped mountains flushed with purple light from the setting sun. As I sat, admiring this splendid scene, the gilded frame of the painting became alive with winged fairies and cherubs, peeping out from behind the moulding, and bending over its margin to look into the picture. Then the ceiling of the room and the sky of the picture seemed to blend in one common expanse of ethereal blue; the sunlight faded from the mountain peaks; stars began to appear in the firmament; the little imps and fairies disappeared; and, presently, everything resumed its natural appearance.

In this experience the departure from healthy cerebral function consisted in an exaltation of certain forms of sensibility while others were depressed. The succession of visual images was initiated by the visible objects around me, but it was enriched by the association of ideas furnished through the stimulation of memory. The sunset glow, the snow-capped mountains, the starry sky, were familiar objects, suggested from memory by the items grouped in the picture. In like manner, the cherubs who climbed upon its gilded frame were merely the glorified products of memory, probably suggested by the fact that it was a picture upon which my attention was fixed—one picture reminding me of others which I had seen. The loss of proportion in the view—the exaggeration and distortion of all the relations of time and space, which made the unreal seem real, and conferred grandeur upon commonplace objects, was undoubtedly occasioned by a modification in the molecular structure of the organs of special sense and of perception under the influence of hasheesh. The change thus effected was of a character to diminish the force of sensory impressions derived through the aid of the muscles and nerves of the eye and the ear and the skin, while at the same time exaggerating the processes of memory and association in connection with impressions originating within the brain. In this way was produced a sort of confusion between the external world and the ideal world within, rendering it difficult to distinguish the one from the other. Hence the impossibility of estimating aright the relation of time and space to the visual impressions upon which attention was fixed. The result was a waking dream which differed from ordinary revery chiefly in the intensity of the impressions that occupied the mind.

A somewhat similar process is sometimes experienced as a consequence of cerebral disorder unconnected with the effects of drugs. During the invasion of measles, having taken no medicine but sage tea, I remember, as night approached, a strange succession of illusions. My head seemed to expand to the size of a bushel basket; then it would slowly contract again. My body seemed to grow out of shape into the most distorted forms of rickets. Audible sounds seemed to come from the most remote distances. Impending shadows of a great darkness hovered over the bed. Waves of heat, and tingling darts of numbness traversed my limbs. These singular and rather uncomfortable sensations continued until relieved by an ordinary Dover’s powder.

In this experience the confusion of ideas, though less agreeable, was essentially similar to that occasioned by the action of the hasheesh. In both cases there was the same diminution of the intensity of external sensation accompanied by an exaggeration of internal impressions. The brain and the nerves were in a condition of irritable weakness, caused by disease, which interfered with the normal generation and association of ideas. Having thus partially escaped from the control of the senses and the will, the mutilated succession of ideas which reached the field of consciousness could only be perceived as a series of illusions. Here, again, was a waking dream, of origin and course analogous to the illusions and hallucinations which accompany every form of delirium.

It is not alone under the influence of disease or of drugs that the automatic action of the brain furnishes ideas for the inspection of the mind. Riding, one day, in a street-car, and reading a philosophical work, I came upon a paragraph devoted to a discussion of the doctrine of the association of ideas. Immediately, out of memory, flashed a momentary vision of the quarter deck of the old frigate, United States, upon which appeared the figure of a very small midshipman, talking to a gigantic personage, the captain of the ship. This was an incident which I had actually witnessed forty years before. I was, at first, somewhat puzzled in the attempt to account for the occurrence of a vision so apparently incongruous with the subject matter of the book; but a little reflection convinced me that the exciting cause of this seemingly involuntary act of memory was really the idea of association suggested by the book. This had unconsciously aroused the apparatus of association in the brain, and the particular scene thus brought before the mind had been further suggested by the circumstance that the last object, external to the printed page, upon which I had fixed my attention, was a large ship, lying in the river, near the bridge, just crossed by the car in which I rode.