From the beginning of recorded history, dreaming has captured the human imagination, as Robert Van de Castle amply demonstrates in his comprehensive history of dreaming, Our Dreaming Mind. The earliest records of dreams come from Mesopotamia, where clay tablets recounting the adventures of the legendary hero Gilgamesh included accounts of dreams and how to interpret their symbolic and metaphorical imagery. The tablets were found in the library of a king who ruled in the seventh century B.C., but oral versions of the dreamrich stories are believed to have circulated hundreds of years earlier. In both India and China by about 1000 B.C., texts had been written on how to decipher the meaning of dreams. These early conceptions of dreams revolved around the notion that they were messages from the gods that could foretell the future, and in many cultures, dreams still are believed to have that power.

The roots of modern scientific thought about dreams can also be found in ancient times. Aristotle proclaimed that, far from being a product of divine origin, “dreaming is thinking while asleep.” The Upanishads, philosophical treatises written in India between 900 and 500 B.C., proposed that it is the dreamer himself who creates horses, chariots, and other objects appearing in the dream world and that dream objects were expressions of the dreamer’s inner desires.

This notion were, of course, at the heart of Sigmund Freud’s dream theory, which dominated both scientific and popular thought about dreams throughout most of the first half of the twentieth century. Freud described dream interpretation as “the royal road to understanding the unconscious activities of the mind.” In his view, the unconscious consisted of both innate information that had never entered consciousness as well as experiences or thoughts that had been shunted off to the unconscious and remain repressed because they were memories, wishes, or fears that were unacceptable. The repressed desire to sleep with one’s mother and kill one’s father became perhaps the iconic example of Freudian theory.

Published in 1900, Freud’s The Interpretation of Dreams argued that dreams spring from subconscious wishes (primarily sexual and aggressive desires, which Freud called libidinal drive) that the censoring ego normally suppressed in waking hours. To protect sleep from being disrupted, the mind then imagined these wishes being fulfilled by creating dreams -symbolic, disjointed tales that were filled with visual metaphors designed to disguise the desires and fears actually being expressed. These wishes sometimes arose from “day residue,” meaning consciously remembered wishes that were aroused during the preceding day but were unfulfilled, or desires bubbling up from the unconscious once sleep relaxed the controlling grip of the mind’s censor.

In Freud’s view, dream symbols had to be translated - with the aid of a psychoanalyst - to uncover meaning. Analysts were taught to use Freud’s technique of “free association” -instructing dreamers to say whatever comes into their minds about each element of the dream without censoring their thoughts. Using free association to decode a dream’s seemingly bizarre, “manifest” content and reveal the uncomfortable hidden truth of its “latent” content were at the heart of Freudian psychoanalysis. A Freudian lexicon developed to explain what various symbols represented. The majority of symbols had sexual connotations, and these have permeated popular culture. It’s difficult to divorce the image of a train entering a tunnel from its Freudian interpretation, a fact that Alfred Hitchcock used to his full advantage in the film North by Northwest, in which a seduction scene between Cary Grant and Eva Marie Saint in a train’s sleeper car cuts abruptly to a shot of the train plunging into a tunnel.

In summarizing his view, Freud stated clearly that “the majority of the dreams of adults deal with sexual material and give expression to erotic wishes.” He contended that “impressions from the earliest year of our life can appear in our dreams, which do not seem to be at the disposal of our memory when we are awake.” In one of his bestknown cases, for instance, Freud concluded that a patient’s dream of seeing wolves sitting in a tree symbolized a traumatic early childhood memory of observing his parents having sex, as well as an underlying fear of castration.

Freud’s insistence that most dream content reflected repressed sexual wishes were one of the major factors leading to the split that occurred between Freud and his one-time protege, Carl Jung, whose dream theories also influenced popular thought on the subject throughout much of the past century. Unlike Freud, Jung did not believe dreams had to be decoded to decipher buried meaning. “The ‘manifest’ dream picture is the dream itself and contains the whole meaning of the dream,” he wrote. Jung believed images in dreams could carry messages from the instinctive, emotional parts of the mind to its rational other half, but they weren’t all disguised symbols representing repressed sexual urges. Often, in fact, dreams express positive desires for growth and development. He proposed analyzing dreams via a process called amplification, in which the personal meanings attached to the dream images are explored by the dreamer himself. If a central image in a dream were a ship, for instance, Jung would ask the dreamer to describe all of the characteristics of the ship as she would if she were speaking to someone who had never seen one before. That way, he could discover what the dreamer’s specific associations to the image were, based on her culture and unique personal history.

In addition to meaning that could be extracted based on each individual’s personal experience, Jung proposed that there were another level of meaning in dreams. In fact, he believed the most important dreams we have are the products of what he called the “collective unconscious,” which reflects the inherited experiential record of the human species. As human anatomy bears telltale signs of its evolutionary past, such as vestiges of a tailbone in the human fetus, so Jung theorized that the mind “can no more be a product without history than is the body in which it exists.” He argued that the collective unconscious was expressed through archetypes that appear not only in dreams but throughout history in the content of myths, fairy tales, and religious ceremony. Archetypal dreams are linked with strong emotions and occur more often around times of crisis or transitions in our lives, Jung contended.

The current revolution in thought about how and why we dream debunks some elements of the theories proposed by both Freud and Jung. But as you’ll see, there are significant pieces of each of their theories that are now supported by scientific evidence. In the past decade, the revolution that began in a dank Chicago laboratory in the mid-1950s has accelerated, thanks to new technologies that allow us to actually see the brain at work even at the molecular level. In labs throughout North America and Europe, and from South Africa to Israel, researchers from fields as diverse as biochemistry, aeronautical engineering, microbiology, and robotics have joined neurophysiologists and psychologists in piecing together the puzzle of the dreaming mind.

The tale of discovery that unfolds in the publications in this category explores how and why we dream, but it may also overturn your assumptions about how the brain does everything from the seemingly straightforward task of seeing a sunset (be it a sunset out there on the horizon or one that’s part of your dreamscape) to more complex jobs such as learning, forming, and retrieving memories or dealing with difficult emotional issues. When your body is safely at rest and your brain therefore no longer needs to process information from the outside world, it is free to focus on other crucial tasks, including integrating new experiences into memory. What happens during this offline processing in turn helps guide your waking behavior.

It has also become clear that dream content can provide valuable information about our deepest preoccupations and feelings. “We have shown that 75 to 100 dreams from a person give us a very good psychological portrait of that individual,” says Bill Domhoff, a psychologist and an expert on a system for quantifying and categorizing dream content that has been used for decades by researchers around the world. “Give us 1,000 dreams collected over a couple of decades and we can give you a psychological profile that is almost as individualized and accurate as fingerprinting.” While some researchers insist that dreaming has no purpose, others argue that the dreaming process itself plays a role in regulating our moods.

If our brains are functioning normally, we do indeed dream each night, even though we recall only a fraction of those internal dramas. Researchers have devised simple methods that can help improve dream recall so that we can peer through this unique window on the mind more frequently. Scientists have also demonstrated that we can increase our ability to become aware that we’re dreaming while a dream is still in progress and sometimes even deliberately control what happens next in the action - a remarkable phenomenon known as lucid dreaming.

During REM sleep, when the majority of dreaming occurs, the brain chemicals that are circulating in abundance are different from those that prevail during waking, as are the regions of the brain that are most active. This dramatically altered operating environment can allow us to make out-of-the-box mental connections that would be rejected by the logical information-processing centers of the brain in command during waking life. The free-form associations that give dreams their sometimes nonsensical quality may also explain why many artists and scientists claim to have come up with breakthrough concepts in dreams.

Ultimately, dream research may also help answer what many consider to be the most intriguing question of all: what is the source of the peculiar brand of self-reflective consciousness that appears to separate humans from other creatures - that nebulous quality that allows us to make intricate plans, fantasize, string memories together to create a personal history, or use abstractions such as language and art to represent our own mental processes? That quest for the roots of consciousness remains at the cutting edge of neuroscientific research today. The answers that are emerging already indicate that the line between dreaming consciousness and waking consciousness is not as rigidly defined as previously thought.

The significance of the new scientific field of dream research were eloquently summarized by Gay Gaer Luce in a U.S.-sponsored report on the state of sleep and dream research in 1965, when the field were first taking off. “For the first time, science is gaining a glimmer of the miraculous machinery of the mind at times when it is speaking only to itself/’ Luce said: “It is not oblivion that is studied in the exploration of sleep, but the entire realm of man’s mental being.”