Sleep and Dreaming

Although dreams have had weighty cultural significance for millennia, factoring heavily in everything from the Bible to the works of Shakespeare to Alice in Wonderland to the psychoanalytical theories of Sigmund Freud, only in the past 60 years or so have scientists begun to understand what really happens in the brain during sleep and dreaming.

Until the 1950s, when researchers discovered the REM (rapid eye movement) stage of sleep during which dreaming takes place, it was believed that the brain was more or less inactive during sleep.

Through countless experiments, psychologists, neuroscientists and other researchers have made great strides in understanding what goes on while people are out for the night. It's clear now that much more happens than was previously thought - but having to rely on subjects' own accounts of their dreams has imposed obvious limitations. There's still much to learn.

» National Institute of Neurological Disorders and Stroke. "Brain Basics: Understanding Sleep."

Dream Symbolism

Most currently accepted ideas about dream symbolism and interpretation descend from the theories of early 20th-century psychiatrists Sigmund Freud and Carl Gustav Jung.

There is also evidence that the Iroquois had dream theories similar to Freud's as early as the 17th century. For example, anthropologists have discovered that Iroquois dream theory reflected a belief that dreams were manifestations of the soul's desires. The Iroquois also believed strongly in the conscious and the unconscious and often talked about or acted out dreams in order to relieve psychosomatic stress.

Freud, who was Austrian, also believed that dreams were a kind of subconscious safety valve, a way to act out unconscious desires, particularly suppressed sexual desires and other primal desires.

Jung, a Swiss native who studied under Freud, believed that Freud's ideas were too simplistic. Jung posited that dreams represented not just unconscious desires, but an entire range of personal and collective unconscious experience.

Freud -- though he is rumored to have said that "sometimes a cigar is just a cigar" -- believed the majority of dream symbolism centered around sex: cylindrical objects from a carrot to a steam engine represented phalluses, while anything cavernous should be read as female genitalia.

Jung, though, believed a figure could have both objective meanings and subjective ones. A snake could represent a penis, as Freud would have claimed, but Jung also considered why the snake in particular appeared as a symbol for that dreamer. Another example: A thief could represent both a literal thief and the dreamer's feelings about crime or dishonesty.

Jung is perhaps best known for his theory of archetypes, or universally understood models or prototypes found throughout folklore, myths and legends from around the world. These could be either figures -- the child, hero, sage, trickster and devil are all examples -- or events such as birth, death, marriage, floods, fires and the apocalypse. Dreams were considered a stage on which the various archetypes could interact.

So in Jung's view, when a person dreamt of a flood or a devil, he was tapping into not only his own ideas of a flood or devil, but also age-old ideas common to the human unconscious.

Jung also proposed the existence of several aspects of the human psyche, building on Freud's ideas concerning the ego, superego and id:

  • The Self, or regulating center and facilitator of individuation
  • The Shadow, the opposite of the ego, possessed of qualities that the ego doesn't recognize
  • The Anima, the feminine within a male
  • The Animus, the masculine within a female
  • The Persona, the image one presents to the world, which acts as a mask

Recent research suggests that when interpreting dreams, what dreamers actually dream (much of which they don't remember) is less important than what they want to believe.

Researchers Carey Morewedge of Carnegie Mellon University and Michael Norton of Harvard University surveyed students in India, South Korea and the United States and found that in all three locations the majority believed, as did Freud, that dreams have important emotional significance and can be valuable omens.

But the subjects were also found to regard the contents of their dreams with bias, assigning more significance to negative dreams if they were about people they disliked, and more weight to positive dreams if they featured people about whom they cared. Religious respondents found more meaning in dreams featuring religious figures than did their secular-minded counterparts.

The researchers coined the term "motivated approach to dream interpretation." When asked if this approach might apply to Freud, Morewedge said, "Freud himself suggested that dreams of flying revealed thoughts of sexual desire. Interestingly, in the same text, Freud also suggested that dreams about the absence of the ability to fly - i.e., falling - also indicate succumbing to sexual desire. One might interpret this as evidence that scientists are just as self-serving as laypeople when interpreting their dreams."

» Jung, C. G. The Archetypes and The Collective Unconscious. Vol. 9. Princeton, N.J.: Princeton University Press, 1981.
» Obringer, Lee Ann. "How Dreams Work." Discovery Health.
» Tierney, John. "What Do Dreams Mean? Whatever Your Bias Says." The New York Times, 9 March 2009.
» Wallace, Anthony F.C. Dreams and Wishes of the Soul: A Type of Psycho-Analytic Theory among the Seventeenth Century Iroquois. New York: Irvington Publishers, 1958.

Neuroscience and Dreaming

The development of brain-scanning techniques such as functional magnetic resonance imaging, which allows researchers to produce images that measure blood flow to different areas of the brain and thus activity in those areas, has been a boon to dream and sleep research in the past couple of decades. These tests allow scientists to see which parts of the brain are used during different stages of sleep and what effects injuries, mental illness and other impairments may have on normal function.

Some of today's more biologically minded researchers would argue that both Freud and Jung are wrong about dreams' real purpose.

According to J. Allan Hobson, a psychiatrist and sleep researcher at Harvard University, the main function of REM sleep is not psychological at all, but rather physiological. Hobson sees it as a time for the brain to warm up its circuits in preparation for the processing of sights, sounds and other stimuli during waking hours. In the 1970s, Hobson and Robert McCarley found that REM sleep is regulated by a kind of switch in the brain stem called the pons that regulates wakefulness but has little to do with mental life. Based on that discovery, Hobson went on to posit that because dreams are caused by a part of the brain divorced from thought processes, dreams are nothing more than random activity in the forebrain and any narratives that a dreamer applies to them are simply efforts to make sense of these disconnected inputs. Hobson argues that the processes that take place during REM sleep are actually taking place all the time, but during waking hours more pressing concerns suppress them.

Other researchers have suggested similarly that dreaming is just what happens when the brain, whose job it is to make sense of the world, receives no external input.

Acceptance of Hobson's theory resulted in a devaluing of Freud's theories, at least in the scientific community, but then Hobson's own ideas were dealt a blow when another researcher, Mark Solms, a professor of neuropsychology at the University of Cape Town, found that people who had suffered damage to the pons continued to dream nevertheless, meaning that the connection between dreaming and REM sleep is not so simple. Solms' theory, in turn, bolstered support for Freud's theory that dreams are the manifestation of unconscious desires.

A more recent theory about the function of dreams comes from Antti Revonsuo, a cognitive neuroscience researcher in Finland. On the basis of research that shows that negative emotions and aggressive interactions are more common in dreams than their positive counterparts, Revonsuo believes that dreams give people a chance to prepare mentally for dangerous situations that may occur in their waking lives.

Recent experiments involving lucid dreaming -- a mixed state in which the subject experiences dreaming but retains some control over what he's seeing -- have been geared to gaining more insight into both the content and neurological processes of dreaming.

For now, most scientists would agree that the true function of dreams -- psychological processing, physiological firings or something in between -- remains elusive. What is clear is that whatever the larger purpose of dreams, they will continue to inspire, calm and bewilder the dreamer with their often highly illogical hodgepodge of memories and personal associations.

» Carey, Benedict. "A Dream Interpretation: Tuneups for the Brain." The New York Times, 9 November 2009.
» National Institute of Neurological Disorders and Stroke. "Brain Basics: Understanding Sleep."
» Obringer, Lee Ann. "How Dreams Work." Discovery Health.