Hypnagogic state

To answer the question, What was perceived we must consider both the possibility that the relevant stimuli were of internal origin and the possibility that the stimuli originated externally to the subject. In the discussion that follows, the assumption of internal stimuli and the possible explanations of suggestion, projection, dreaming, and hypnagogic state will be taken up first, followed by a consideration of the hypotheses of sensory translation and reality transfer. Then, assuming external stimuli, the hypothesis of perceptual expansion will be presented. 

Examples of dissociations of consciousness that often divide the waking mind into two compartments include microsleeps, attentional lapses, and fantasy states. At the edges of sleep are hypnagogic hallucinations and sleep paralysis. Within sleep are sleep walking, sleep talking, and lucid dreaming. In all of these conditions, consciousness has some features characteristic of one state mixed with features characteristic of another. 

One of the most instructive examples of state boundary crossing is the tendency to experience dreamlike visuomotor sensations at sleep onset. These are called hypnagogic hallucinations if the subject is still awake enough to notice or be aroused by them. Apparently, one need only carry waking brain activation over the sleep boundary and dreaming will im-... 

This normalizing account of hypnagogic hallucinations lends itself nicely to explanation in terms of AIM and hence to integration with those spontaneous and induced alterations in conscious state that interest us most. For example, an exaggeration of the normal tendency to hallucinate at sleep onset is seen in narcolepsy, as well as with the use of clinical and recreational drugs that alter the M axis of the AIM model in ways that promote REM sleep phenomena, including the intense dreaming often associated with it. 

Many narcoleptic patients show a marked intensification of sleep onset REM physiology, making the enhancement of hypnagogic hallucinations easily understandable. Because narcolepsy is also associated with the occurrence of hallucinations on awakening from REM sleep, I will defer discussion of the clinical aspects of the disorder until we have considered these hypnopompic extensions of dreaming into the wake state. 

The d-ASCs experienced by almost all ordinary people are dreaming states and the hypnagogic and hypnopompic states, the transitional states between sleeping and waking. Many others experience another d-ASC, alcohol intoxication. 

Narcolepsy is a chronic neurological disorder and is characterised by excessive daytime sleepiness (EDS), usually accompanied by cataplexy (attacks of weakness on emotional arousal). These symptoms are often associated with the intrusion into wakefulness of other elements of rapid eye movement (REM) sleep, such as sleep paralysis and hypnagogic hallucinations, i.e. in a transient state preceding sleep. 

Ibid., 55. Technically, "hypnagogic" is defined as the state of intermediate consciousness while going to sleep, while the state of intermediate consciousness while awakening is called "hypnopompic."... 

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