Insomnia; and Other Disorders of Sleep

by Henry M. Lyman

Numerous other examples of a similar character might be related to illustrate the fact that the brain is a reservoir of sensory impressions, some of which, at the moment of their original incidence, have aroused the mind to a greater or less degree of conscious attention, and have then all lapsed into a latent or potential condition. But, though latent, they are none the less persistent, and only await the suppression of other inhibitory forces to become once more capable of arousing attention. Such inhibitory impulses are continually furnished by the action of the sensory organs on the one hand, and by the energy of the mind upon the other. So soon, therefore, as the organs of sense and of voluntary impulse are sealed with sleep, if the remaining portions of the brain are still operative, and are left to their own unrestrained activity, a more or less disorderly series of ideas occupies the mind. This constitutes a dream. The difference, therefore, between waking thought and a dream is analogous to the difference between a page upon which the words have been arranged in a rational order, and another page upon which some of the same words have been set down at random. Inasmuch as the majority of our sensations are derived through the organs of sight, and since the larger portion of the sensory region of the cortex of the brain is concerned in the act of vision, it is no more than might be expected that the ideas suggested in sleep should generally proceed from the visual apparatus of the brain. The superior power of visual impressions to attract attention may also serve to explain the fact that the majority of dreams are composed of images that were originally perceived in the act of vision. Hence our dreams, for the most part, constitute a series of pictures undisturbed by sound, or by other forms of sensation. But this is not always so. It is highly probable that when the organs of external sense are allowed to sleep without disturbance, our dreams consist of visual impressions alone. But, if any unusual sound, or smell, or other sensation is experienced during sleep, it may penetrate the field of consciousness, and may become the starting point of a dream quite filled with sounds. Thus a young lady, who had passed the evening at a musical concert, was aroused, soon after retiring, by the striking of a clock which had been recently placed in her chamber. At the moment of waking, she was dreaming of an orchestral performance of Wagner’s music. Doubtless the dream was suggested by the unaccustomed sound of the clock.

The possibility of thus suggesting, and in some degree guiding, the form and course of a dream, has been often demonstrated.[58] One of my early schoolmates, a boy of remarkably susceptible nervous temperament, furnished an excellent example of this species of direction. Tickling his nose with a straw made him dream that a dragon-fly was assaulting his face. On another occasion, a few drops of vinegar placed upon his tongue caused him to dream of eating oranges. Again, one of his companions roguishly breathing in his ear the statement that the schoolmaster was after him with a long rattan, he bounded out of bed, and could scarcely be restrained from bursting out of doors in his evident alarm. I was myself awakened, one night, by the ringing, as it seemed, of my doorbell; but, hastening at once to the door, no one was there. As I was expecting a call from a certain patient, I concluded that the bell had been rung by an impatient messenger who could not wait. Falling again asleep, I was a second time startled by a similar ring. Looking out of the window above the door, it was evident that no one was there. I finally concluded that the sound must have been perceived in a dream, and I recalled the fact that each time, as I woke, the sound of a carriage, passing the house, had attracted my attention. Undoubtedly, the state of expectancy in which I was sleeping had operated as the predisposing cause of dreaming, and the noise of wheels upon the pavement had served as the exciting cause of a dream in which the sound-vibrations communicated to the brain had produced by an association of ideas the particular perception which, though asleep, I was waiting to receive.

In certain cases the impression produced by a dream is so vivid that a considerable time after waking must elapse before it can be relegated to its true position in the world of hallucinations. Dreaming, once, that my wife called to me from another room, I instantly awoke; and only the fact that she was with me could satisfy me that it was all a dream. Taine[59] relates that “M. Baillarger dreamed one night that a certain person had been appointed editor of a newspaper; in the morning he believed it to be true, and mentioned it to several persons who were interested to hear it;—the effect of the dream persisted all the forenoon, as strongly as that of a real sensation; at last, about three o’clock, as he was stepping into his carriage, the illusion passed off; he comprehended that he had been dreaming.”

The following incident from the experience of Prof. Jessen, physician to the insane asylum in Homheim, near Kiel,[60] still further illustrates this form of hallucination:

“On a wintry morning,” writes the professor, “between five and six o’clock, I was aroused, as I thought, by the head nurse, who reported to me that some people had come for one of the male patients, and who at the same time asked me whether I had any particular orders to give. I replied that the patient might depart, and after he had left the room I turned around to go to sleep again. All at once it struck me that I had previously not heard anything regarding the intended departure of this patient, but that only the prospective departure of a woman of the same name had been reported to me. This compelled me to inquire more particularly after the circumstances, and accordingly I lighted a candle, rose, dressed myself, and went to the room of the head nurse. To my surprise I found him only half dressed, and, in reply to my inquiry after the people who had called for the patient, he said, with an expression of astonishment, that he did not know anything of it, as he had but just left his bed, and no one had called him. This answer did not arouse my consciousness, but I rejoined that then the steward must have been in my room, and that I should accordingly go to see and ask him regarding the matter. When descending a few steps in the middle of the corridor which led to the room of the steward, I suddenly became conscious of having dreamed only what until that moment I had believed to be an experience whose reality I had not doubted in the least.”

In some instances the fact of having dreamed is never recognized, and the dreamer carries through life the delusion that his vision was an actual occurrence. Among the Indians of Guiana, and the same thing is true of many other savages, dreams are looked upon as actual events in which the dreamer is visited by spirits or even by other living men. A recent English traveler[61] says: “It becomes important, therefore, fully to recognize the complete belief of the Indian in the reality of his dream-life, and in the unbroken continuity of this with his working life. It is easy to show this belief by many incidents which came under my notice. For instance, one morning, when it was important to me to get away from a camp on the Essequibo River, at which I had been detained for some days by the illness of some of my Indian companions, I found that one of the invalids, a young Macusi, though better in health, was so enraged against me that he refused to stir, for he declared that, with great want of consideration for his weak health, I had taken him out during the night and had made him haul the canoe up a series of difficult cataracts. Nothing could persuade him that this was but a dream, and it was some time before he was so far pacified as to throw himself sulkily into the bottom of the canoe. At that time we were all suffering from a great scarcity of food, and hunger having its usual effect in producing vivid dreams, similar effects frequently occurred. More than once the men declared in the morning that some absent men, whom they named, had come during the night and had beaten or otherwise maltreated them; and they insisted upon much rubbing of the bruised parts of their bodies.”

It is highly probable that from these facts, and from others of a similar character, may be derived the true explanation of many of the supposed examples of intercourse with divine or angelic persons which occupy so important a place in early mythology. An incident in the childhood of the prophet Samuel can scarcely admit of any other interpretation. In other cases, notwithstanding the intensity of the dream, its true character is recognized by the dreamer during the very act of vision. Thus, I once dreamed that I saw a young girl standing before me. So vivid was the perception, that the actual presence of such a person could not have produced a more perfect impression upon the waking brain. Yet, at the same instant, I comprehended the fact that it was merely a dream, and remarked the difference between the intensity of the visual image in this and in other dreams. Such speedy recognition of the hallucination does not always accompany the act of waking out of a dream. In some cases, as we shall have occasion to see, the images which have figured in a dream are still perceived for a certain period of time after awaking.

The majority of dreams are composed of visual images. The dreamer looks upon a picture which changes silently before his eyes, without appealing to any other sense than that of sight. But in certain cases any other sense may become excited, producing illusions or hallucinations as perfect as the images of healthy vision. They may be suggested by external impressions, as in my dream of a ring at the door bell, which proved to be an auditory illusion excited by the sound of passing carriage wheels; or they may, at least apparently, find their starting point in accidental states of the bodily organization. If attention be paid to this matter, it will be observed that all unusual modes of dreaming, and all extraordinary vividness of dream-impressions can be connected with some departure from the physiological conditions of quiet sleep. Either disease, or exhaustion, or emotional disturbance, or narcotic intoxication of the brain may be noted as the immediate cause of such derangement of the cerebral functions. After drinking several cups of coffee before retiring, I dreamed of a large yellow flower which exhaled a very fragrant odor. During the same night I also dreamed of drinking wine, which agreeably excited the senses of taste and of smell. Upon another occasion, having been disturbed by the entrance of burglars into my house, I dreamed that a burglar was fumbling under my pillow, and was raising my head and shoulders with the mattress upon which I slept. I seemed to feel the changes of pressure and of contact as distinctly as if awake. The connection of voluptuous illusions with erotic dreams is too familiar to require particular mention.

Dreams are not always limited to the revival and combination of the images of sensation. Intellectual combinations are sometimes thus presented to the mind. The most familiar illustrations of this fact are furnished by the experience of mathematicians who have worked out mathematical problems in their dreams. One of my patients, an expert book-keeper, dreamed of adding up six columns of figures at once. In the morning he still remembered his dream; and, on adding up the columns, found that he had actually produced the right sum in each case. A college student of my acquaintance, who was puzzled by a geometrical proposition, wrote out the correct solution during his sleep. This was something more than simple dreaming; it trenched upon actual somnambulism. Another acquaintance dreamed of being in heaven, and, while there, experienced relief from doubt regarding certain theological doctrines which had previously exercised his mind. I have myself composed several sentences during the course of a dream, and have, while dreaming, sometimes esteemed them worthy of preservation; but my waking recollection has never coincided in this particular with the opinions formed during sleep.

Great difference between dreams may be remarked in their coherence and continuity of evolution. Some are composed of the most inconsistent elements without order or logical arrangement. In others the incidents follow very closely in the line of a natural and rational development, so that the dreamer seems to be present as a spectator of a perfectly coherent drama. It is probable that these differences depend upon variations in the degree of completeness with which the different parts of the brain and of the body are overwhelmed by sleep. If different and widely separated portions are sufficiently wakeful to suggest ideas to the mind, the resulting congeries will consist of discordant and incoherent elements. But if wakefulness is limited to a particular organ of the body or to a circumscribed territory of the brain, the resulting impressions in consciousness should be correspondingly restricted, and will manifest a more orderly connection with each other. In some cases a tendency to simultaneous wakefulness of particular portions of the cerebral register seems to become habitual, so that the same set of ideas may be often renewed in the same order during sleep, constituting a repetition of the same dream. In this way I have frequently dreamed of a volcanic eruption of molten lava from a lofty mountain. This frequent revival of the same train of images is probably due to the fact that in childhood I actually witnessed a volcanic outbreak, and that a very highly colored picture of Vesuvius in eruption hangs in my sitting room, so that my brain has become profoundly impressed with this particular image. When other portions of the brain are asleep, if the special region concerned with this picture be aroused, the mind receives the same impression which it received when first excited by that portion of the organ of memory.