DREAM
A dream is a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep.
A painting depicts a man dreaming of being a king, shown inside the thought bubble.
A dream is a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep.[1]
Humans spend about two hours dreaming per night,[2] and each dream lasts around 5 to 20 minutes, although the dreamer may perceive the dream as being much longer than this.[3]
The content and function of dreams have been topics of scientific, philosophical and religious interest throughout recorded history.
Dream interpretation, practiced by the Babylonians in the third millennium BCE[4] and even earlier by the ancient Sumerians,[5][6] figures prominently in religious texts in several traditions, and has played a lead role in psychotherapy.[7][8]
The scientific study of dreams is called oneirology.[9]
Most modern dream study focuses on the neurophysiology of dreams and on proposing and testing hypotheses regarding dream function.
It is not known where in the brain dreams originate, if there is a single origin for dreams or if multiple regions of the brain are involved, or what the purpose of dreaming is for the body or mind.
The human dream experience and what to make of it has undergone sizable shifts over the course of history.[10][11]
Long ago, according to writings from Mesopotamia and Ancient Egypt, dreams dictated post-dream behaviors to an extent that was sharply reduced in later millennia.
These ancient writings about dreams highlight visitation dreams, where a dream figure, usually a deity or a prominent forebear, commands the dreamer to take specific actions, and which may predict future events.[12][13][14]
Framing the dream experience varies across cultures as well as through time.
Dreaming and sleep are intertwined.
Dreams occur mainly in the rapid-eye movement (REM) stage of sleep—when brain activity is high and resembles that of being awake.
Because REM sleep is detectable in many species, and because research suggests that all mammals experience REM,[15] linking dreams to REM sleep has led to conjectures that animals dream.
However, humans dream during non-REM sleep, also, and not all REM awakenings elicit dream reports.[16]
To be studied, a dream must first be reduced to a verbal report, which is an account of the subject's memory of the dream, not the subject's dream experience itself.
So, dreaming by non-humans is currently unprovable, as is dreaming by human fetuses and pre-verbal infants.[17]
Oneirology (/ɒnɪˈrɒlədʒi/; from Greek ὄνειρον, oneiron, "dream"; and -*λογία, -*logia, "the study of") is the scientific study of dreams.
Current research seeks correlations between dreaming and current knowledge about the functions of the brain, as well as understanding of how the brain works during dreaming as pertains to memory formation and mental disorders.
The study of oneirology can be distinguished from dream interpretation in that the aim is to quantitatively study the process of dreams instead of analyzing the meaning behind them.
History
In the 19th century, two advocates of this discipline were the French sinologists Marquis d'Hervey de Saint Denys and Alfred Maury.
The field gained momentum in 1952, when Nathaniel Kleitman and his student Eugene Aserinsky discovered regular cycles.
A further experiment by Kleitman and William C. Dement, then another medical student, demonstrated the particular period of sleep during which electrical brain activity, as measured by an electroencephalograph (EEG), closely resembled that of waking, in which the eyes dart about actively.
This kind of sleep became known as rapid eye movement (REM) sleep, and Kleitman and Dement's experiment found a correlation of 0.80 between REM sleep and dreaming.
Field of work
Research into dreams includes exploration of the mechanisms of dreaming, the influences on dreaming, and disorders linked to dreaming.
Work in oneirology overlaps with neurology and can vary from quantifying dreams, to analyzing brain waves during dreaming, to studying the effects of drugs and neurotransmitters on sleeping or dreaming.
Though debate continues about the purpose and origins of dreams, there could be great gains from studying dreams as a function of brain activity.
For example, knowledge gained in this area could have implications in the treatment of certain mental illnesses.