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Dreams
are a series of images, ideas, emotions, and sensations occurring involuntarily in the mind during certain stages of sleep. [1] The content and purpose of dreams are not fully understood, though they have been a topic of speculation and interest throughout recorded history. The scientific study of dreams is known as oneirology.
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DREAM TICKETS
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Cultural history
Dreams have a long history, both as a subject of conjecture and as a source of inspiration. Throughout history, people have sought
meaning in dreams or
divination through dreams. They have been described
physiologically as a response to neural processes during sleep,
psychologically as reflections of the
subconscious, and
spiritually as messages from
gods or predictions of the future. Many cultures had practiced
dream incubation, with the intention of cultivating dreams that were
prophetic or contained messages from the
divine.
Judaism has a traditional ceremony called "hatavat halom" – literally meaning making the dream a good one. Through this rite disturbing dreams can be transformed to give a positive interpretation by a rabbi or a rabbinic court.
[2]
Neurology of sleep and dreams
There is no universally agreed biological definition of dreaming. In 1952
Eugene Aserinsky discovered
REM sleep while working in the surgery of his
PhD advisor. Aserinsky noticed that the sleepers' eyes fluttered beneath their closed eyelids, later using a
polygraph machine to record their
brain waves during these periods. In one session he awakened a subject who was wailing and crying out during REM and confirmed his suspicion that dreaming was occurring.
[3] In 1953 Aserinsky and his advisor published the ground-breaking study in
Science
.
[4]
Accumulated observation shows that dreams are strongly associated with
rapid eye movement (REM) sleep, during which an
electroencephalogram shows brain activity to be most like wakefulness. Participant-nonremembered dreams during
non-REM sleep are normally more mundane in comparison.
[5] During a typical lifespan, a human spends a total of about six years dreaming
[6] (which is about two hours each night).
[7] Most dreams last only 5 to 20 minutes.
It is unknown where in the brain dreams originate, if there is a single origin for dreams or if multiple portions of the brain are involved, or what the purpose of dreaming is for the body or mind.
During REM sleep, the release of certain neurotransmitters is completely suppressed. As a result,
motor neurons are not stimulated, a condition known as
REM atonia. This prevents dreams from resulting in dangerous movements of the body.
Animals have complex dreams and are able to retain and recall long sequences of events while they are asleep.
[8] Studies show that various species of mammals and birds experience REM during sleep,
[9] and follow the same series of sleeping states as humans.
Despite their power to bewilder, frighten us or amuse us, dreams are often ignored in mainstream models of cognitive psychology.
[10] As methods of introspection were replaced with more self-consciously objective methods in the social sciences in 1930s and 1940s, dream studies dropped out of the scientific literature. Dreams were neither directly observable by an experimenter nor were subjects’ dream reports reliable, being prey to the familiar problems of distortion due to delayed recall, if they were recalled at all. More often dreams are, of course, forgotten entirely, perhaps due to their (according to
Freud) prohibited character. Altogether these problems seemed to put them beyond the realm of science.
The discovery that dreams take place primarily during a distinctive electrophysiological state of sleep, rapid eye movement (REM) sleep, which can be identified by objective criteria, led to rebirth of interest in this phenomenon. When REM sleep episodes were timed for their duration and subjects woken to make reports before major editing or forgetting could take place, it was determined that subjects accurately matched the length of time they judged the sleep the dream narrative to be ongoing to the length of REM sleep that preceded the awakening. This close correlation of REM sleep and dream experience was the basis of first series of reports describing the nature of dreaming: that it is regular nightly, rather than occasional, phenomenon, and a high-frequency activity within each sleep period occurring at predictable intervals of approximately every 60–90 minutes in all humans throughout the life span. REM sleep episodes and the dreams that accompany them lengthen progressively across the night, with the first episode being shortest, of approximately 10–12 minutes duration, and the second and third episodes increasing to 15–20 minutes. Dreams at the end of the night may last as long as 15 minutes, although these may be experienced as several distinct stories due to momentary arousals interrupting sleep as the night ends. Dream reports can be reported from normal subjects on 50% of the occasion when an awakening is made prior to the end of the first REM period. This rate of retrieval is increased to about 99% when awakenings are made from the last REM period of the night. This increase in the ability to recall appears to be related to intensification across the night in the vividness of dream imagery, colors and emotions. The dream story itself in the last REM period is farthest from reality, containing more bizarre elements, and it is these properties, coupled with the increased likelihood of spontaneous arousals allowing waking review to take place, that heighten the chance of recall of the last dream.
Dream theories
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