An artist's imaginary depiction of a dream.
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.
Mechanisms of dreaming
Dreaming occurs mainly during REM sleep, and brain scans recording brain activity have witnessed heavy activity in the limbic system and the amygdala
during this period. Though current research has reversed the myth that
dreaming occurs only during REM sleep, it has also shown that the dreams
reported in non-rapid eye movement (NREM) and REM differ qualitatively and quantitatively, suggesting that the mechanisms that control each are different.
During REM sleep, researchers theorize that the brain goes
through a process known as synaptic efficacy refreshment. This is
observed as brain waves self-firing during sleep, in slow cycles at a
rate of around 14 Hz, and is believed to serve the purpose of
consolidating recent memories and reinforcing old memories. In this type
of brain stimulation, the dreaming that occurs is a by-product of the
process.
Stages of sleep
During
normal sleep cycles, humans alternate between normal, NREM sleep and
REM sleep. The brain waves characteristic of dreaming that are observed
during REM sleep are the most commonly studied in dream research because
most dreaming occurs during REM sleep.
REM sleep
EEG showing brainwaves during REM sleep
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. In 1953, Aserinsky and his advisor published the ground-breaking study in Science.
Accumulated observation shows that dreams are strongly associated with REM sleep, during which an electroencephalogram
shows brain activity to be most like wakefulness.
Participant-nonremembered dreams during NREM are normally more mundane
in comparison. During a typical lifespan, a human spends a total of about six years dreaming (which is about two hours each night). 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, 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. Studies show that various species of mammals and birds experience REM during sleep, and follow the same series of sleeping states as humans.
The discovery that dreams take place primarily during a
distinctive electrophysiological state of sleep (REM), 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 awakened 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 dream narrative to occupy with the
length of REM sleep that preceded the awakening. This close correlation
of REM sleep and dream experience was the basis of the first series of
reports describing the nature of dreaming: that it is a regular nightly
occurrence, rather than an occasional phenomenon, and that it is 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 the 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
typically 15 minutes, although these may be experienced as several
distinct stories due to momentary arousals interrupting sleep as the
night ends.
Dream reports can normally be made 50% of the time when an
awakening occurs prior to the end of the first REM period. This rate of
retrieval is increased to about 99% when awakenings occur during 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 morning waking review to take place, that heighten the
chance of recall of the last dream.
Definition of a dream
The
definition of dream used in quantitative research is defined through
four base components: 1) a form of thinking that occurs under minimal
brain direction, external stimuli are blocked, and the part of the brain
that recognizes self shuts down; 2) a form of experience that we
believed we experience through our senses; 3) something memorable; 4)
have some interpretation of experience by self. In summary, a dream, as
defined by Bill Domhoff and Adam Schneider, is "a report of a memory of a
cognitive experience that happens under the kinds of conditions that
are most frequently produced in a state called 'sleep.' "
Commonplace bizarreness in dreaming
Certain kinds of bizarre cognitions, such as disjunctive cognitions and interobjects, are common in dreams.
Interobject
Interobjects,
like disjunctive cognitions, are a commonplace bizarreness of
dreamlife. Interobjects are a kind of dream condensation that creates a
new object that could not occur in waking life. It may have a vague
structure that is described as "something between an X and a y". Hobson dreamt of "a piece of hardware, something like the lock of a door or perhaps a pair of paint-frozen hinges."
Authentic dreaming
Authentic dreams are defined by their tendency to occur "within the realm of experience"
and reflect actual memories or experiences the dreamer can relate to.
Authentic dreams are believed to be the side effect of synaptic efficacy
refreshment that occurs without errors.
Research suggests that the brain stimulation that occurs during
dreaming authentic dreams is significant in reinforcing neurological
pathways, serving as a method for the mind to "rehearse" certain things
during sleep.
Illusory dreaming
Illusory
dreams are defined as dreams that contain impossible, incongruent, or
bizarre content and are hypothesized to stem from memory circuits
accumulating efficacy errors. In theory, old memories having undergone
synaptic efficacy refreshment multiple times throughout one's lifetime
result in accumulating errors that manifest as illusory dreams when
stimulated. Qualities of illusory dreaming have been linked to delusions observed in mental disorders.
Illusory dreams are believed to most likely stem from older memories
that experience this accumulation of errors in contrast to authentic
dreams that stem from more recent experiences.
Influences on dreaming
One
aspect of dreaming studied is the capability to externally influence
the contents of dreams with various stimuli. One such successful
connection was made to the olfactory,
influencing the emotions of dreams through a smell stimulus. Their
research has shown that the introduction of a positive smelling stimulus
(roses) induced positive dreams while negative smelling stimulus
(rotten eggs) induced negative dreams.
Memories and experience
Though there is much debate within the field about the purpose of dreaming, a leading theory involves the consolidation of memories and experiences that occurs during REM sleep. The electric involuntary stimulus the brain undergoes during sleep is believed to be a basis for a majority of dreaming.
The link between memory, sleep, and dreams becomes more
significant in studies analyzing memory consolidation during sleep.
Research has shown that NREM sleep is responsible for the consolidation of facts and episodes in contrast to REM sleep that consolidates more emotionally related aspects of memory.
The correlation between REM and emotional consolidation could be
interpreted as the reason why dreams are of such an emotional nature and
produce strong reactions from humans.
Interpersonal attachment
In
addition to the conscious role people are aware of memory and
experience playing in dreaming, unconscious effects such as health of
relationships factor into the types of dreams the brain produces. Of the
people analyzed, those suffering from "insecure attachments" were found
to dream with more frequency and more vividly than those who were
evaluated to have "secure attachments."
Drugs affecting dreaming
Correlations
between the usage of drugs and dreaming have been documented,
particularly the use of drugs, such as sedatives, and the suppression of
dreaming because of drugging effects on the cycles and stages of sleep
while not allowing the user to reach REM. Drugs used for their stimulating properties (cocaine, methamphetamine, and ecstasy) have shown to also decrease the restorative properties of REM sleep and its duration.
Dreaming disorders
Dreaming
disorders are difficult to quantify due to the ambiguous nature of
dreaming. However, dreaming disorders can be linked to psychological
disorders such as post-traumatic stress disorder expressed as nightmares. Research into dreaming also suggests similarity and links in illusory dreaming and delusions.
Post-traumatic stress disorder
Diagnostic
symptoms include re-experiencing original trauma(s), by means of
flashbacks or nightmares; avoidance of stimuli associated with the
trauma; and increased arousal, such as difficulty falling or staying
asleep, anger, and hypervigilance.
Links to post-traumatic stress disorder (PTSD) and dreaming have been made in studying the flashbacks
or nightmares the victims would suffer. Measurement of the brain waves
exhibited by the subjects experiencing these episodes showed great
similarity between those of dreaming. The drugs used to treat those
suffering from these symptoms of flashbacks and nightmares would
suppress not only these traumatic episodes but also any other sort of
dreaming function.
Schizophrenia
The symptoms of schizophrenia involve abnormalities in the perception or expression of reality primarily focused on delusions and hallucinations.
The delusions experienced by those with schizophrenia have been
likened to the experience of illusory dreams that have come to be
interpreted by the subject as actual experiences. Additional research into medication to suppress symptoms of schizophrenia have also shown to influence the REM cycle of those taking the medication and as a result influence the patterns of sleep and dreaming in the subjects.
