The term hypnopompic hallucination is indebted to the Greek words hupnos (sleep) and pem-pein (to accompany, to send away). It translates roughly as 'a hallucination that accompanies the individual when leaving the sleeping state'. The term was introduced in or shortly before 1892 by the British classical scholar, writer, and poet Frederic Myers (1843-1901) to denote a hallucination that accompanies the departure of sleep, "as when a dream-figure persists for a few moments into waking life". Hypnopompic hallucinations (as well as their logical counterpart, referred to as " hypnagogic hallucinations) are perceptual phenomena taking place in the intermediate state between wakefulness and sleep. Taken together, hypnopompic and hypnagogic hallucinations are referred to as " hypnagogia. Hypnopompic hallucinations are regularly occurring phenomena in individuals with and without a mental disorder. Some studies indicate that their incidence may increase significantly with the use of - or withdrawal from - therapeutics such as tri-cyclic antidepressants and opioids. An increased incidence has also been reported in association with various psychiatric and neurological disorders, including "narcoplepsy, anxiety disorders, depressive disorder, bipolar disorder, and adjustment disorder. Although primarily visual in nature, they can manifest themselves in any of the sensory modalities. When Myers defined the term hypnopompic hallucination, he appeared to reserve it primarily for visual phenomena (i.e. hypnopompic imagery). Common examples of hypnopompic imagery include a person standing at the foot of the bed, a face hovering over one's bed, and an intruder cowering in the corner of the room. Anticipatory scenes have been reported as well, such as seeing oneself getting out of bed, and starting one's typical early morning routine. When accompanied by the conviction that one is actually awake, such anticipatory hallucinations are designated as " false awakenings. Hypnopompic hallucinations can also take the form of auditory percepts, notably in the form of speech or music which continue for a while after one has awoken. Hypnopompic hallucinations in general can be accompanied by " hallucinoid experiences such as " sensed presence, " incubus, or " illusory movement experiences. Phenomenolog-ically, hypnopompic hallucinations meet all the Esquirolian criteria for hallucinations except that they occur during the transitional phase between wakefulness and sleep. As a consequence, they have traditionally been set apart from the class of " hallucinations proper. As regards pathophys-iology, the mediation of hypnopompic hallucinations is associated primarily with instances of " REM sleep occurring in the absence of other REM phenomena. Therefore, they have also been designated as REM dissociation phenomena. In a phenomenological, and possibly a pathophys-iological sense as well, hypnopompic hallucinations would seem to be related to "desert hallucinations.
References
Cheyne, J.A. (2001). The ominous numinous. Sensed presence and 'other' hallucinations. Journal of Consciousness Studies, 8, 133-150. Mavromatis, A. (1987). Hypnagogia. The unique state ofconsciousness between wakefulness and sleep. London: Routledge.
Myers, F.W.H. (1903). Human personality and its survival of bodily death. Volume I. London: Longmans, Green, and Co.
Schiller, F. (1985). The inveterate paradox of dreaming. Archives of Neurology, 42, 903-906.
Watkins, M. (2003). Waking dreams. Third edition. Putnam, CT: Spring Publications.
Dictionary of Hallucinations. J.D. Blom. 2010.