Dreaming
I INTRODUCTION
Dreaming,
form of mental activity, different from waking thought, that occurs during
sleep. The nature of dream activity has been characterized by many clinical and
laboratory studies. These studies show that dreams are more perceptual than
conceptual: Things are seen and heard rather than thought. In terms of the
senses, visual experience is present in almost all dreams; auditory experience
in 40 to 50 percent; and touch, taste, smell, and pain in a relatively small
percentage. A considerable amount of emotion is commonly present—usually a
single, stark emotion such as fear, anger, or joy rather than the modulated
emotions that occur in the waking state. Most dreams are in the form of
interrupted stories, made up partly of memories, with frequent shifts of scene.
This broad characterization
includes a great variety of dream experiences. Many dreams collected in sleep
laboratories are rather ordinary, but most people have at least some bizarre
dreams. At the start of the 20th century Sigmund Freud proposed that a mental
process quite different from that used in the waking state dominates the
dreaming mind. He described this "primary process" as characterized by
more primitive mechanisms, by rapid shifts in energy and emotions, and by a good
deal of sexual and aggressive content derived from childhood.
II BIOLOGY
OF DREAMING
Research
in recent years has clarified many of these aspects of dreaming, but what may be
of greatest significance has been the discovery of a biology of dreaming (see
Sleep). Starting with the work of American
sleep researchers Eugene Aserinsky and Nathaniel Kleitman in 1953, studies have
shown that a dream does not consist of fleeting imagery that occurs while a
person awakens from sleep, but instead a dream takes place during a biological
state of its own.
Thus, two clearly
distinguishable states of sleep exist. The first state, called S-synchronized
sleep, or NREM-sleep (non-rapid-eye-movement sleep), occupies most of the sleep
period and is associated with a relatively low pulse and blood pressure, little
activation of the autonomic nervous system, and few or no reports of dreaming.
The second type of sleep, known as D-sleep (dreaming, or desynchronized, sleep),
or REM-sleep (rapid-eye-movement sleep), occurs cyclically during the sleep
period and is characterized by activation of the autonomic nervous system, rapid
eye movements, and frequent dream reports. Typically, a person has four or five
periods of D-sleep during the night, whether the dreams are remembered often,
rarely, or not at all; they occur at intervals of about 90 minutes and
altogether constitute about 25 percent of the night’s sleep (as much as 50
percent in a newborn child). Evidence indicates that a dream period usually
lasts from 5 to 20 minutes.
Such stimuli as sounds and touches impinging on a dreamer can be
incorporated into a dream if they occur during a D-period. These stimuli,
however, do not initiate a D-period if one is not already in progress, so that,
at least in such cases, dreams do not protect sleep in the way that Freud
suggested. Although mental activity may be reported during NREM-sleep, these are
usually short, fragmented, thoughtlike experiences.
III OTHER
ANIMALS
It is likely that other
animals dream. Mammals, including dogs, cats, and monkeys, have D-sleep periods
like those of humans. During D-sleep they also show intense activity in a region
of the brain called the visual cortex. In humans this brain activity corresponds
to visual sensations. One study observed monkeys that were trained to push a
lever whenever they saw a picture on a screen. At different times during their
sleep the monkeys suddenly began to push the lever as if responding to an
observed image.
IV THE
MEANING OF DREAMS
Ancient
cultures believed that dreams were spiritual in origin, often foretelling the
future. Aristotle believed that dreams originated from within the dreamer,
arising from the heart. Modern dream research has focused on two general
interpretations of dream content. In one view, dreams have no inherent meaning
but are simply a process by which the brain integrates new information into
memories. In the other view, dreams contain real meaning symbolized in a picture
language that is distinct from conscious logical thought.
The recounting of dreams has
been used widely as part of clinical treatment. If dreams express important
wishes, fears, concerns, and worries of the dreamer, the study and analysis of
dreams can help reveal previously unknown aspects of a person’s mental
functioning.
Contributed By:
Ernest Louis Hartmann
