Hypnagogia

Hypnagogia

Hypnagogia or hypnagogic hallucinations refer to the experiences during the transitional state from wakefulness to sleep. During this phase, individuals might experience hallucinations, lucid thought, lucid dreaming, and sleep paralysis. The opposite transitional state, from sleep to wakefulness, is known as hypnopompic.

Definitions

The term "hypnagogia" is sometimes used to describe the onset of sleep, while "hypnopompia" refers to waking up. However, hypnagogia can also be employed in a broader sense, covering both falling asleep and waking up. Other terms related to hypnagogia include "presomnal," "anthypnic sensations," "visions of half-sleep," "oneirogogic images," "phantasmata," "borderland of sleep," "praedormitium," "half-dream state," "pre-dream condition," "sleep onset dreams," "dreamlets," and "wakefulness-sleep transition" (WST).

Threshold consciousness refers to the mental state of someone transitioning toward sleep or wakefulness but has not yet completed the transition. These transitions can be brief or extended by sleep disturbances or deliberate induction, like during meditation.

Signs and symptoms

Hypnagogia can be accompanied by a wide range of sensory experiences in any modality, from barely perceptible to vivid hallucinations.

Sights

Commonly reported visual features of hypnagogia include phosphenes, which can appear as random speckles, lines, geometrical patterns, or even figurative images. They can be monochromatic or colored, still or moving, and flat or three-dimensional. Hypnagogic imagery is usually static and lacking in narrative content but can evolve into more complex scenes.

Tetris effect

Individuals who spend a long time engaging in repetitive activities before sleep might find that the activity dominates their imagery as they become drowsy. This phenomenon is called the Tetris effect and can manifest in different sensory modalities, such as touch or auditory sensations.

Sounds

Auditory hypnagogic hallucinations can range from faint impressions to loud noises like knocking, crashes, or bangs. Individuals might hear their name called, imagine speech fragments, or even hear poetry or music.

Other sensations

Gustatory, olfactory, and thermal sensations have been reported during hypnagogia, along with tactile sensations and synesthesia. Changes in perceived body size, proportions, and out-of-body experiences might occur, as well as the common falling sensation and associated hypnic jerk.

Cognitive and affective phenomena

Thought processes during hypnagogia tend to differ from those during wakefulness. Hypnagogic cognition is characterized by heightened suggestibility, illogic, and fluid association of ideas. The state might provide insights into problems or inspire creativity.

Physiology

Hypnagogia is typically associated with stage 1 of NREM sleep and can occur with pre-sleep alpha waves. The state might resemble a mix of REM sleep and relaxed wakefulness in terms of EEG power spectra.

History

Early references to hypnagogia appear in the writings of Aristotle, Iamblichus, Cardano, Simon Forman, and Swedenborg. The term "hypnagogic" was coined by Alfred Maury to describe the state of consciousness during sleep onset, while "hypnopompic" was coined by Frederic Myers to describe the onset of wakefulness. Hypnagogia became more widely known in popular psychology literature through Dr. Andreas Mavromatis's 1983 thesis.

Hypnagogia and related experiences

Sleep paralysis

Sleep paralysis is a separate condition that is sometimes experienced during the hypnagogic state. It is characterized by the inability to move or speak during the transition between sleep and wakefulness. Sleep paralysis can be a distressing experience, as it may be accompanied by vivid hallucinations and a sense of dread or fear. However, it is important to note that sleep paralysis is a normal and harmless phenomenon that affects many people at some point in their lives.

Lucid dreaming

Lucid dreaming is another phenomenon that may occur during the hypnagogic state. It refers to the experience of becoming aware that one is dreaming while still in the dream state. This heightened awareness allows the dreamer to exert some control over the dream's content and direction. Lucid dreaming is a skill that can be developed with practice, and it has been associated with increased creativity and problem-solving abilities.

See also

• Sleep
• Dream
• REM sleep
• Meditation

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