Oneirology

thumb|right|An artist's depiction of a dream

In the field of psychology, the subfield of oneirology (; ) is the scientific study of dreams. Research seeks correlations between dreaming and knowledge about the functions of the brain, as well as an understanding of how the brain works during dreaming with respect 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 for 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. 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. While REMS is associated with dreaming, not all REMS periods result in reported dreams, and not all dreams occur during REMS. 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.

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.

Authentic dreaming

Authentic dreams are defined by their tendency to occur "within the realm of experience" 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.

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. Research suggests that dreams, especially during REM sleep, help consolidate memories by integrating new information with existing memories. This process may prioritize emotionally significant or unresolved experiences.

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 been 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.