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Hypnagogia
Hypnagogia is the experience of the transitional state from wakefulness to sleep: the ''hypnagogic'' state of consciousness, during the onset of sleep. Its opposite state is described as the transitional state from sleep into wakefulness. Mental phenomena that may occur during this "threshold consciousness" phase include hypnagogic hallucinations, lucid thought, exploding head syndrome, lucid dreaming, and sleep paralysis. The latter two phenomena are themselves separate sleep conditions that are sometimes experienced during the hypnagogic state. Definitions The word ''hypnagogia'' is sometimes used in a restricted sense to refer to the onset of sleep, and contrasted with ''hypnopompia'', Frederic Myers's term for waking up. However, ''hypnagogia'' is also regularly employed in a more general sense that covers both falling asleep and waking up. Indeed, it is not always possible in practice to assign a particular episode of any given phenomenon to one or the other, given that the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hallucination
A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combination of 2 conscious states of brain wakefulness and REM sleep. They are distinguishable from several related phenomena, such as dreaming ( REM sleep), which does not involve wakefulness; pseudohallucination, which does not mimic real perception, and is accurately perceived as unreal; illusion, which involves distorted or misinterpreted real perception; and mental imagery, which does not mimic real perception, and is under voluntary control. Hallucinations also differ from "delusional perceptions", in which a correctly sensed and interpreted stimulus (i.e., a real perception) is given some additional significance. Many hallucinations happen also during sleep paralyses. Hallucinations can occur in any sensory modality—visual, auditory, olfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sleep Paralysis
Sleep paralysis is a state, during waking up or falling asleep, in which one is conscious but is completely paralyzed. During an episode, one may hallucinate (hear, feel, or see things that are not there), which often results in fear. Episodes generally last less than a couple of minutes. It can recur or occur as a single episode. The condition may occur in those who are otherwise healthy or those with narcolepsy, or it may run in families as a result of specific genetic changes. The condition can be triggered by sleep deprivation, psychological stress, or abnormal sleep cycles. The underlying mechanism is believed to involve a dysfunction in REM sleep. Lucid dreaming doesn't affect the chances of sleep paralysis but some lucid dreamers use this as a method of having a lucid dream. Diagnosis is based on a person's description. Other conditions that can present similarly include narcolepsy, atonic seizure, and hypokalemic periodic paralysis. Treatment options for sleep para ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Form Constants
A form constant is one of several geometric patterns which are recurringly observed during hypnagogia, hallucinations and altered states of consciousness. History In 1926, Heinrich Klüver systematically studied the effects of mescaline (peyote) on the subjective experiences of its users. In addition to producing hallucinations characterized by bright, "highly saturated" colors and vivid imagery, Klüver noticed that mescaline produced recurring geometric patterns in different users. He called these patterns "form constants" and categorized four types: lattices (including honeycombs, checkerboards, and triangles), cobwebs, tunnels, and spirals. In 1988 David Lewis-Williams and T.A. Dowson incorporated the form constant into his Three Stages of Trance model, the geometric shapes comprising the visuals observed in the model's first stage. Precipitants Klüver's form constants have appeared in other drug-induced and naturally occurring hallucinations, suggesting a similar physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sleep Onset
Sleep onset is the transition from wakefulness into sleep. Sleep onset usually transmits into non-rapid eye movement sleep (NREM sleep) but under certain circumstances (e.g. narcolepsy) it is possible to transit from wakefulness directly into rapid eye movement sleep (REM sleep). History During the 1920s an obscure disorder that caused encephalitis and attacked the part of the brain that regulates sleep influenced Europe and North America. Although the virus that caused this disorder was never identified, the psychiatrist and neurologist Constantin von Economo decided to study this disease and identified a key component in the sleep-wake regulation. He identified the pathways that regulated wakefulness and sleep onset by studying the parts of the brain that were affected by the disease and the consequences it had on the circadian rhythm. He stated that the pathways that regulated sleep onset are located between the brain stem and the basal forebrain. His discoveries were not appreci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetris Effect
The ''Tetris'' effect (also known as ''Tetris'' syndrome) occurs when people devote so much time and attention to an activity that it begins to pattern their thoughts, mental images, and dreams. It takes its name from the video game ''Tetris''. People who have played ''Tetris'' for a prolonged amount of time can find themselves thinking about ways different shapes in the real world can fit together, such as the boxes on a supermarket shelf or the buildings on a street. They may see colored images of pieces falling into place on an invisible layout at the edges of their visual fields or when they close their eyes. They may see such colored, moving images when they are falling asleep, a form of hypnagogic imagery. Those experiencing the effect may feel they are unable to prevent the thoughts, images, or dreams from happening.Stickgold, R., interviewed 30 October 2000 by Norman Swan for ''The Health Report'' on Australia's Radio Nationaltranscript. Retrieved 15 January 2020. A m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Somnolence
Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling asleep, the condition of being in a drowsy state due to circadian rhythm disorders, or a symptom of other health problems. It can be accompanied by lethargy, weakness and lack of mental agility. Somnolence is often viewed as a symptom rather than a disorder by itself. However, the concept of somnolence recurring at certain times for certain reasons constitutes various disorders, such as excessive daytime sleepiness, shift work sleep disorder, and others; and there are medical codes for somnolence as viewed as a disorder. Sleepiness can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When a person is sufficiently fatigued, microsleeps may be experienced. In individuals deprived of sleep, somno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mental Image
A mental image is an experience that, on most occasions, significantly resembles the experience of 'perceiving' some object, event, or scene, but occurs when the relevant object, event, or scene is not actually present to the senses. There are sometimes episodes, particularly on falling asleep ( hypnagogic imagery) and waking up ( hypnopompic imagery), when the mental imagery may be dynamic, phantasmagoric and involuntary in character, repeatedly presenting identifiable objects or actions, spilling over from waking events, or defying perception, presenting a kaleidoscopic field, in which no distinct object can be discerned. Mental imagery can sometimes produce the same effects as would be produced by the behavior or experience imagined. The nature of these experiences, what makes them possible, and their function (if any) have long been subjects of research and controversy in philosophy, psychology, cognitive science, and, more recently, neuroscience. As contemporary researche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perspective (visual)
Linear or point-projection perspective (from la, perspicere 'to see through') is one of two types of graphical projection perspective in the graphic arts; the other is parallel projection. Linear perspective is an approximate representation, generally on a flat surface, of an image as it is seen by the eye. Perspective drawing is useful for representing a three-dimensional scene in a two-dimensional medium, like paper. The most characteristic features of linear perspective are that objects appear smaller as their distance from the observer increases, and that they are subject to ''foreshortening'', meaning that an object's dimensions along the line of sight appear shorter than its dimensions across the line of sight. All objects will recede to points in the distance, usually along the horizon line, but also above and below the horizon line depending on the view used. Italian Renaissance painters and architects including Masaccio, Paolo Uccello, Piero della Francesca and Luca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Figurative Art
Figurative art, sometimes written as figurativism, describes artwork (particularly paintings and sculptures) that is clearly derived from real object sources and so is, by definition, representational. The term is often in contrast to abstract art: Since the arrival of abstract art the term figurative has been used to refer to any form of modern art that retains strong references to the real world. Painting and sculpture can therefore be divided into the categories of figurative, representational and abstract, although, strictly speaking, abstract art is derived (or abstracted) from a figurative or other natural source. However, "abstract" is sometimes used as a synonym for non-representational art and non-objective art, i.e. art which has no derivation from figures or objects. Figurative art is not synonymous with figure painting (art that represents the human figure), although human and animal figures are frequent subjects. Formal elements The formal elements, those aestheti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monochromatic
A monochrome or monochromatic image, object or color scheme, palette is composed of one color (or lightness, values of one color). Images using only Tint, shade and tone, shades of grey are called grayscale (typically digital) or Black and white, black-and-white (typically analog). In physics, Monochromatic radiation, monochromatic light refers to electromagnetic radiation that contains a narrow band of wavelengths, which is a distinct concept. Application Of an image, the term monochrome is usually taken to mean the same as black and white or, more likely, grayscale, but may also be used to refer to other combinations containing only tones of a single color, such as green-and-white or green-and-red. It may also refer to Sepia tone, sepia displaying tones from light tan to dark brown or cyanotype ("blueprint") images, and early photographic methods such as daguerreotypes, ambrotypes, and tintypes, each of which may be used to produce a monochromatic image. In computing, monoc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wakefulness
Wakefulness is a daily recurring Human brain, brain state and state of consciousness in which an individual is conscious and engages in coherent cognition, cognitive and behavioral responses to the external world. Being awake is the opposite of being asleep, in which most external inputs to the brain are excluded from neural processing. Effects upon the brain The longer the brain has been awake, the greater the synchronous firing rates of cerebral cortex neurons. After sustained periods of sleep, both the speed and synchronicity of the neurons firing are shown to decrease. Another effect of wakefulness is the reduction of glycogen held in the astrocytes, which supply energy to the neurons. Studies have shown that one of sleep's underlying functions is to replenish this glycogen energy source. Maintenance by the brain Wakefulness is produced by a complex interaction between multiple neurotransmitter systems arising in the brainstem and ascending through the midbrain, hypothalam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eigengrau
Eigengrau (German for "intrinsic gray"; ), also called Eigenlicht (Dutch and German for "intrinsic light"), dark light, or brain gray, is the uniform dark gray background color that many people report seeing in the absence of light. The term ''Eigenlicht'' dates back to the nineteenth century, but has rarely been used in recent scientific publications. Common scientific terms for the phenomenon include "visual noise" or "background adaptation". These terms arise due to the perception of an ever-changing field of tiny black and white dots seen in the phenomenon. Eigengrau is perceived as lighter than a black object in normal lighting conditions, because contrast is more important to the visual system than absolute brightness. For example, the night sky looks darker than Eigengrau because of the contrast provided by the stars. Cause Researchers noticed early on that the shape of intensity-sensitivity curves could be explained by assuming that an intrinsic source of noise in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
