Figures or objects may suddenly zoom towards one, getting larger and more detailed, then retreat. Hypnagogic images, often compared to snapshots or slides, flash into consciousness, hold for a second or two, then disappear; they may be replaced by other images that seem to have no connection or apparent association to one another.
Hypnagogic visions may seem like something from “another world” — this phrase is used again and again by people describing their visions. Edgar Allan Poe stressed the fact that his own hypnagogic images were not only unfamiliar but unlike anything he had ever seen before; they had “the absoluteness of novelty.”2
Most hypnagogic images are not like true hallucinations: they are not felt as real, and they are not projected into external space. And yet they have many of the special features of hallucinations — they are involuntary, uncontrollable, autonomous; they may have preternatural colors and detail and undergo rapid and bizarre transformations unlike those of normal mental imagery.
There is something about the rapid and spontaneous transformations specific to hypnagogic imagery that suggests the brain is “idling,” as my correspondent Mr. Utter suggested. Neuroscientists now tend to speak of “default networks” in the brain, which generate their own images. Perhaps one may also venture the term “play” and think of the visual cortex playing with every permutation, playing with no goal, no focus, no meanings — a random activity or perhaps an activity with so many microdeterminants that no pattern is ever repeated. Few phenomena give such a sense of the brain’s creativity and computational power as the almost infinitely varied, ever-changing torrent of patterns and forms which may be seen in hypnagogic states.
Although Mavromatis writes of hypnagogia as “the unique state of consciousness between wakefulness and sleep,” he sees affinities with other states of consciousness — those of dreams, meditation, trance, and creativity — as well as the altered modes of consciousness in schizophrenia, hysteria, and some drug-induced states. Although hypnagogic hallucinations are sensory (and thus cortical, being produced by the visual cortex, auditory cortex, etc.), he feels that the initiating processes may be in the more primitive, subcortical parts of the brain, and this, too, is something that hypnagogia may share with dreams.
And yet the two are quite distinct. Dreams come in episodes, not flashes; they have a continuity, a coherence, a narrative, a theme. One is a participant or a participant-observer in one’s dreams, whereas with hypnagogia, one is merely a spectator. Dreams call on one’s wishes and fears, and they often replay experiences from the previous day or two, assisting in the consolidation of memory. They sometimes seem to suggest the solution to a problem; they have a strongly personal quality and are determined mostly from above — they are largely “top-down” creations (although, as Allan Hobson argues, with a wealth of supporting evidence, they also employ “bottom-up” processes). In contrast, hypnagogic imagery or hallucination, with its largely sensory qualities — enhanced or exaggerated color and detail and outlines, luminosity, distortions, multiplications, and zoomings — and its detachment from personal experience, is overwhelmingly a “bottom-up” process. (But this is a simplification, for given the two-way traffic at every level in the nervous system, most processes are both top-down and bottom-up.) Hypnagogia and dreaming are both extraordinary states of consciousness, as different from each other as they are different from waking consciousness.
Hypnopompic hallucinations — those that may come upon waking — are often profoundly different in character from hypnagogic hallucinations.3 Hypnagogic hallucinations, seen with closed eyes or in darkness, proceed quietly and fleetingly in their own imaginative space and are not usually felt to be physically present in one’s room. Hypnopompic hallucinations are often seen with open eyes, in bright illumination; they are frequently projected into external space and seem to be totally solid and real. They sometimes give amusement or pleasure, but they often cause distress or even terror, for they may seem charged with intentionality and ready to attack the just-wakened hallucinator. There is no such intentionality with hypnagogic hallucinations, which are experienced as spectacles unrelated to the hallucinator.
While hypnopompic hallucinations are only occasional with most people, they may occur frequently in some, as is the case with Donald Fish, an Australian man whom I met in Sydney after he wrote to me about his vivid hallucinations:
