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Closed-eye hallucinations and closed-eye visualizations (CEV) are a distinct class of hallucination. These types of hallucinations generally only occur when one's eyes are closed or when one is in a darkened room. They can be a form of phosphene. Certain users report closed-eye hallucinations under the influence of psychedelics. These are reportedly of a different nature than the "open-eye" hallucinations of the same compounds. Closed eye hallucination is directly related to a chronic type.
Levels of CEV perception 
There are five known levels of CEV perception which can be achieved either through chemical stimuli or through meditative relaxation techniques. Level 1 and 2 are very common, and often happen every day. It is still normal to experience level 3, and even level 4, but only a small percentage of the population do this without psychedelic drugs, meditation or extensive visualization training.
Level 1: Visual noise 
The most basic form of CEV perception that can be immediately experienced in normal waking consciousness involves a seemingly random noise of pointillistic light/dark regions with no apparent shape or order.
This can be seen when the eyes are closed and looking at the back of the eyelids. In a bright room, a dark red can be seen, owing to a small amount of light penetrating the eyelids and taking on the color of the blood within them. In a dark room, blackness can be seen or the object can be more colourful. But in either case it is not a flat unchanging redness/blackness. Instead, if actively observed for a few minutes, one becomes aware of an apparent disorganized motion, a random field of lightness/darkness that overlays the redness/blackness of your closed eyelids.
For a person who tries to actively observe this closed-eye perception on a regular basis, there comes a point where if he or she looks at a flat-shaded object with his or her eyes wide open, and tries to actively look for this visual noise, he or she will become aware of it and see the random pointillistic disorganized motion as if it were a translucent overlay on top of what is actually being seen by his or her open eyes.
When seen overlaid onto the physical world, this CEV noise does not obscure physical vision at all, and in fact is hard to notice if the visual field is highly patterned, complex, or in motion. When active observation is stopped, it is not obvious or noticeable, and seemingly disappears from normal physical perception. Individuals suffering from visual snow see similar noise but experience difficulty blocking it from conscious perception.
Level 2: Light/dark flashes 
Some mental control can be exerted over these closed-eye visualizations, but it usually requires a bit of relaxation and concentration to achieve.   When properly relaxed it is possible to cause regions of intense black, bright white or even colors such as yellow, green, or pink to appear in the noise. These regions can span the entire visual field, but seem to be fleeting in nature.
Level 3: Patterns, motion, and color 
This level is relatively easily accessible to people who use LSD, and appears to be what most people refer to as colourful visuals.
However, it is also accessible to people involved in deep concentration for long. When lying down at night and closing the eyes, right before sleep the complex motion of these patterns can become directly visible without any great effort thanks to hypnagogic hallucination. The patterns themselves might resemble fractals.
Level 4: Objects and things 
This is a fairly deep state. At this level, thoughts visually manifest as objects or environments. When this level is reached, the CEV noise seems to calm down and fade away, leaving behind an intense flat ordered blackness. The visual field becomes a sort of active space. A side component of this is the ability to feel motion when the eyes are closed.
Some paranormal researchers believe that remote places can be viewed in this state and have named it remote viewing.
Opening the eyes returns one to the normal physical world, but still with the CEV object field overlaid onto it and present. In this state it is possible to see things that appear to be physical objects in the open-eye physical world, but that aren't really there.
|“||If we remember that the essential difference between what we call the real world and the world of imagination and hallucination, is not the elements of which we build them up but the sequence in which these elements appear... then it follows that the sequences directed from without represent a limitation of the otherwise unlimited combinations of the selective forms released at random from within||”|
Level 5: Overriding physical perception 
If inducing by drugs or mental disease, this is the point where it appears to the outside world that a person is either unconscious or insane. The internal CEV perceptions and think-it/feel-it perceptions become stronger than physical perceptions, and completely override and replace open-eye physical perceptions. This can be a potentially dangerous state if a person is still mobile while in a different imagined world, but by this time most people are motionless and not likely to do something hazardous to themselves or others. This is the point where most hallucinogenic references say it is a good idea to have a "sitter" present to watch over the person using the chemicals, and keep them from accidentally harming themselves or others while deep into their own world.
According to lucid dreaming researcher Stephen LaBerge, perceptions can come from either the senses or imagination. A inhibitory system involving in the thalamus, likely involving serotonergic neurons, inhibits imaginary perceptions from becoming too activated so they turn into hallucinations. This system is inhibited during REM sleep, and the imagination can freely run into the perceptual systems. What happens at level 5 is likely that this system is inhibited, just like in REM sleep, by different causes like sensory deprivation, psychedelic drugs or meditative relaxation techniques. 
What is not a CEV 
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Image burn-in (afterimage) 
Image burn-in occurs when very bright objects lie in one's field of vision, and should not be confused with closed-eye hallucinations. Visual burn-in from bright lights is visible for a few minutes after closing the eyes, or by blinking repeatedly, but the burn-in effect slowly fades away as the retina recovers, whereas the waking-consciousness CEV noise will not disappear if observed continuously over a period of time.
Corneal liquid 
CEV does not involve the liquid and air bubbles on the surface of the cornea, which can also be seen by extremely nearsighted people when looking at bright point-light sources with glasses/contacts removed. Also called "Floaters" - often appear as cells floating across the eye. Half-closing and reopening the eyelids creates a very definite wiper-ridge in the corneal liquid that is readily visible. Fully closing and reopening the eyelids also stirs up the corneal liquid which settles down after a brief moment. The motion of waking-consciousness CEV noise is not so directly and physically controllable and repeatable. This is not necessarily only associated with extreme nearsightedness.
Blue-sky sprites 
CEV does not seem to be related to the "sprites" (blue field entoptic phenomenon) that can be seen as dots darting around when staring up into a bright blue sky on a sunny day (not looking at the sun). These dots superimposed over a flat blue background are white blood cells moving through the blood vessels of the retina. The motion of waking-consciousness CEV noise is uniformly random compared to the waking-consciousness blue-sky sprite motion.
Physical retinal stimulation 
CEV is unrelated to the visual noise seen when the retina is physically stimulated. The retina can be made to produce light patterns of visual noise simply by one rubbing their eyes somewhat forcefully in a manner that increases intraocular pressure. Additionally retinal noise can be produced by touching near the rear of the eyeball (for example, if one closes their eyes, looks all the way left, and lightly touches the rightmost part of the eye socket, this produces visual noise in the shape of a circle that appears at the left side of the visual field - a practice that is neither painful nor dangerous). None of these are closed-eye hallucinations.
See also 
- Ladd, Trumbull (1894). "Direct control of the retinal field.". Psychological Review. Retrieved 28 September 2012.
- Ladd, Trumbull (1903). "Direct control of the'retinal field': Report on three cases.". Psychological Review. Retrieved 28 September 2012.
- Neal, Richard McKenzie (2008). The Path to Addiction: And Other Troubles We are Born to Know. AuthorHouse. pp. 228–231. ISBN 1-4389-1674-4.
- Moskvitin, Jurij (1974). Essay on the origin of thought. Ohio University Press. ISBN 0-8214-0156-4.
- "Sleep Paralysis".
- Lilly, John C. (1990). The Center of the Cyclone. Marion Boyars Publishers Ltd. ISBN 0-7145-0961-2
- Lilly, John C. (1981). The Deep Self: Profound Relaxation and the Tank Isolation Technique. Warner Books. ISBN 0-446-33023-X
- Stephen LaBerge (1990). "Lucid Dreaming: Psychophysiological Studies of Consciousness during REM Sleep". Sleep and Cognition. American Psychological Association. Retrieved 20 September 2012.