We spend about a third of our lives asleep and a large part of that time we are dreaming. Yet we usually don't remember our dreams, or soon forget them after we are awake. As a result a large part of our lives is inaccessible to our conscious mind.
There are many theories about the cause and purpose of dreaming, as well as theories about what dreams mean. Below we have reprinted an interesting article about dreams which was published in Chamber's Cyclopedia of Universal Knowledge around 1899. Despite many scientific advances since then, we have still not cracked the code to understanding dreams and their meaning.
Dreaming may be defined as the manifestation of conscious mental activity during sleep.
It is probable that during the profoundest sleep there is a complete suspension of all forms of conscious activity. Our senses cease to respond to ordinary stimuli, we cannot will any act or originate any thought, and we are unconscious of our own existence. At the same time, all reflex acts are lowered, breathing and the action of the heart become slower, and the other organic functions are also diminished. These phenomena are due to the exhaustion of the energy of the brain, and to the changes necessary for its restoration, and for the removal of tissue waste. They are accompanied by a diminution of the amount of blood flowing through the organ. As we go to sleep, our senses drop off one by one, we cease to see or smell, while we still continue to hear. Even during sleep our faculties may not fall equally into abeyance. A light sleeper may, without waking, answer questions put to him. Men may sleep on horseback or on the march, the central nervous mechanism co-ordinating the necessary movements | alone remaining awake and active. Again, as is well known, an expected sound, however light, may arouse one oblivious to all other noises. It is obvious then that during sleep there may be all degrees of abolition of activity in the various faculties. Some may be in full power, while the others are completely or partially suspended. We dream then because our Drain is in a condition of partial activity. It is maintained by some that no sleep is ever so profound as to be perfectly dreamless. Sir William Hamilton thought that we dream always, but simply forget our dreams. This proposition, which obviously cannot be proved, is supported by the fact that we forget with the utmost readiness what we know we have dreamed, and that others may see in our actions evidence of dreaming of which we ourselves afterwards retain no recollection. Many facts in connection with injuries to the head point, however, in an opposite direction. Dr Maudsley quotes the case of a boy who was rendered insensible by the kick of a horse. After trephining the depressed bone he became sensible. The surgeon took advantage of the hole in the skull to make firm pressure on the exposed brain after asking him a question. While the pressure lasted he remained silent, but the instant it was removed he made a reply, never suspecting that he had not answered at once. With regard to the time at which we dream there has been much discussion. Many consider that we dream only in the semi-conscious state of falling asleep or of awakening. This unquestionably is true in many cases, but the evidence of somnambulism (sleep walking) and of the night terrors of children would indicate that we may dream at any time; and, moreover,we may find ourselves dreaming awakened out of a deep slumber.
The ideas constituting our dreams may, in rare cases, be coherent complicated trains of thought. Mathematical problems ineffectually attacked during the day have been solved in this way, legal opinions given on difficult questions, and sermons composed and written. Many such cases are recorded by trustworthy persons. Coleridge composed the poem of Kubla Khan during a three hours’ sleep, and wrote out on awakening the existing fragment, extending to fifty-four lines, which, but for an accidental interruption, might have reached two or three hundred. In most cases, however, there is no apparent cohesion in the sequence of our ideas. The control of the will or power of forming common-sense or moral judgments, is more or less completely lost. The most improbable events do not surprise us. Miss Cobbe (Macmillan's Magazine, 1870) narrates how Mr Richard Napier, one of the most benevolent of men, dreamt he ran his best friend through the body, and ever afterwards recalled the gratification with which he saw the point of the sword come out through his shoulder. The philanthropist commits cruel acts without remorse. All distinction of time and place is lost, we converse with the dead, we are transported thousands of miles in a moment, and so on ; and we take it all as a matter of course, or have at the most a feeling of slight wonder. The rapidity of the sequence of our ideas is one of the most remarkable of the phenomena of dreaming. This may be compared with the similar condition which sometimes occurs during the act of drowning, when the whole of one’s past life may be mirrored on the mind in a moment. Dreams which seem to cover months, or even years, take place within a few seconds or minutes.
It is well known that a sound which may awake a sleeper, may at the same time give origin to a dream which apparently covers a long period of time. As already mentioned, many of our most complicated dreams take place during the act of wakening. On the other hand, it must not be imagined that all dreams are mere momentary occurrences. Every one who has watched a dog dreaming knows over how long a time the act may be prolonged, as is indicated by the succession of yelping and barking movements. It is not perfectly accurate to say that the will and the judgment are altogether in abeyance. We may find ourselves voluntarily prolonging a pleasant dream, which we recognise as such; and we may by a similar process awaken ourselves so as to interrupt a disagreeable or depressing one.
The subject-matter of dreams is always composed of previous mental experiences, the majority of which are obtained through the sense of sight. For the most part they are those of recent date, perhaps those of the day preceding. But not rarely old and forgotten experiences may be recalled by associations the clue to which is quite lost. A momentary and possibly hardly noticed sensation during the day, may, during sleep, recall the ideas associated with an occasion long ago when the same sensation was experienced. It is an interesting question how the deaf and the blind dream. Dr Darwin records the case of a gentleman who had been deaf for thirty years, and who never dreamt of persons conversing with him except by the fingers or in writing, and never had the impression of hearing them speak. Mr Johns, in the National Review for 1885, states that the blind, who can of course have no visual images, dream as actively as those who see, and dream by hearing, and touching, and smelling; they tell the size of a room by the sound of imaginary persons walking in it; recognise a friend by his voice, or by touch
ing him; or the freshness of the morning by the smell of the air.
Dreams sometimes may be directly ascribed to impressions on the special senses. Thus it is told of Dr Gregory that he dreamt of ascending the crater of Mount Etna, after having gone to sleep with a bottle of hot water at his feet.
A French observer, Maury, bad a series of experiments conducted on himself to determine whether special sense-impressions would always produce ¦corresponding dreams. He directed a person to make various experiments on his senses, and to awaken him soon after each. When his lips and nose were tickled with a feather, be dreamt that the skin of his face was being tom off with a pitch plaster. Pinching the hack of his neck made him dream of a doctor who had blistered him there in his infancy. In many of his observations, however, no connection could he traced between the dream and its immediate cause. The special character of many dreams is determined by the condition of the organs of the thorax and abdomen, and of the muscular system. For example, the presence of indigestible or undigested food in the stomach, by embarrassing the breathing and the action of the heart, suggests the ideas of the various forms of nightmare, the monster, or the crushing weight from which there is no escape, which are closely akin to the sensations induced by similar effects on the heart during the day. An uncomfortable position in bed, a strained condition of the muscular system, will cause dreams of falling over precipices or of struggling. Certain well-known drugs give a specific character to dreams. The magnificent visions of the opium stupor have been made familiar by the classical account of De Quincey.
(It is well to mention that the splendour of the dreams is not so certain to follow the indulgence of the opium habit as is the degradation of our mental and moral and physical nature.) The furious homicidal delirium caused by hashish (Indian Hemp )
is indicated by its being the origin of the name Assassin (q.v.). Excessive indulgence in alcohol gives rise to delirious dreams characterised by unfounded dread and suspicion. Workers in india-rubber factories, who are exposed to the inhalation of bisulphide of carbon, suffer from fearful dreams of being murdered and falling over precipices. Many other drugs induce almost as certain results.
The state of the circulation and that of the nervous tissue of the brain are important factors whose influence can hardly be separated. Sound sleep, like sound thought, is impossible either with an over-congested brain, or in one with a deficient supply of blood. In the former case, there is a tendency to a rapid succession of vivid dreamings, interrupted by intervals of wakefulness. The brain cells are too excited by the excess of blood to pass into a condition of repose, and their activity | tends to keep up the congestion of the organ. When the blood is deficient in quantity or in quality, or poisoned by substances which ought to be removed from the body, and when the nervous system is exhausted by such causes as over-fatigue, shock, or depressing emotions from over-indulgence in any form, then unpleasant depressing dreams are apt to follow.
The onset of acute disease (especially when affecting the nervous system) is not infrequently heralded by continued dreaming or continued sleeplessness. Depressing dreams should be always regarded as an indication of need for attention to health, or to relaxation from work, more especially, perhaps, by those engaged in professional pursuits.
With regard to the effect of dreams, many, no doubt, are forgotten utterly : some, forgotten during the waking state, are vividly recalled during
Many, perhaps most, areindistinctly remembered for a short a time: others again, like the dream of Clarence, produce an ineradicable impression of reality:
I trembling waked, and for a season after Could not believe but that I was in hell,
Such terrible impression made my dream.
In some forms, which may be named somnambulic dreams, in which the dream is acted as well as thought out, it is remarkable that almost no recollection is retained. Such cases are familiar to us in their mildest forms, in the child talking, crying, or using his fists in his sleep. The night terrors of nervous children, so frequent during their second dentition, often cause unnecessary anxiety. In these, the child may start up suddenly out of a sound sleep, manifesting signs of pain or terror. After a time, generally without waking, the child lies down, and in the morning has no recollection of the occurrence. Under this category must also be included acts of unconscious violence occurring during sleep, which sometimes lead to most distressing consequences. Dr Clouston of Morningside, Edinburgh, refers to a case where a confirmed somnambulist during his sleep seized his child, to whom he was devotedly attached, and caused his death by dashing him against the wall, under the belief that he saw a wild animal in the room. The man in question was acquitted on the charge of murder, it being held that he was not responsible during sleep. The condition might be described as one of sanity during the waking hours, and of the opposite during sleep. Many similar cases are on record. They are generally indications of a strong hereditary tendency to instability of the nervous system. See Somnambulism.
Among the peoples of antiquity, dreams were regarded as direct messages from the spiritual world, of either divine or diabolical origin, and their interpretation was elevated to the rank of a science. Nowadays the tendency is to explain away the undoubted facts of foretelling the future on the ground of mere coincidence. It would be marvellous if among the multitude of dreams having reference to the future some did not come true. Such cases arrest the attention, while others are forgotten. To the writer it appears that this latter explanation of mere coincidence cannot be accepted. He would regard the apparent foretelling of the future as on a par with the working out of a problem by the mathematician. In the former case, it is the solution during sleep of the question that has been occupying the mind of the deep political, moral, or religious thinker. The anxieties connected with a "low Nile" would give rise to the dream of Pharaoh as certainly as would the mental tension of Condorcet lead to his continuing his mathematical calculations during sleep. What the ancients considered a direct message from God we term the working of the natural law. In neither case is the matter one of chance or mere coincidence.
See Abercrombie’s Inquiries concerning the Intellectual i Powers (1830); Seafield’s Literature and Curiosities of Dreams (1869); Carpenter’s Mental Physiology (1881); Maudsley’s Pathology of Mind (1879), and his Natural \ Causes and Supernatural Seemings (1886).