The Dream Drugstore, by J. Allan Hobson, is a fascinating book. It is a serious monograph written in a popular style whose major argument is that one can understand the entire range of conscious states by mastering several critical underlying neurochemical and neural mechanisms.

Dr. Hobson made his dramatic entry into the psychiatric literature in 1977 with the publication of the first credible rebuttal of Freud's theory of dreams, accompanied by an elegant, scientifically sound alternative hypothesis. Since then, from his position as director of the neurophysiology laboratory at the Massachusetts Mental Health Center and professor of psychiatry at Harvard University, he has continued to study sleep and to publish extensively.

Dr. Hobson believes that the mind and the body are intertwined and that the subjective experience that some have called mind is but a manifestation of brain activity. The chemical balance of various neurotransmitters and regulators shifts periodically during the day, activating specific brain areas and causing different states of mind. Psychotherapeutic and psychedelic drugs affect consciousness through the same mechanisms that are responsible for the daily shifts in the normal brain. Consequently, one can derive a unified theory that explains normal dreaming, drug-induced visions, and psychotic states.

Dr. Hobson outlines what is known about consciousness; describes the normal fluctuations that characterize wakefulness, dreaming, and the switch from one state to the next; and relates these fluctuations to the chemical alterations found in depression and schizophrenia. Similar chemical changes determine the reactions to ingested hallucinogens.

Dr. Hobson's starting point is the study of dreams. Dreams are an altered state of consciousness characterized by a series of changes that distinguishes them from waking. Dreams involve diminished self-awareness and attention as well as an abundance of delusional and bizarre beliefs, probably occasioned by the inhibition of the dorsolateral prefrontal cortex neurons and by cholinergic predominance. Dreams are also characterized by loss of working memory, caused in part by low norepinephrine and serotonin levels, and enhancement of past memory secondary to disinhibition of networks that store mnemonic representations. Visual imagery is enhanced in dreams, probably as a result of activation of higher visual centers.

Dr. Hobson has constructed a model of dreaming to help us understand various states of consciousness. The AIM model is based on the interplay between three crucial brain attributes of consciousness: arousal-activation, source of information (excitation by real-world events versus brain-generated messages), and modulation (changes induced by cholinergic or serotonergic and noradrenergic transmitters). Normal, drug-induced, and pathological states can all be placed in the space created by these three dimensions, thus demonstrating their affinity. One can intentionally alter states of consciousness by manipulating any one of the three dimensions. For example, one can change the source of excitation as in hypnosis, trance, relaxation, and meditation or one can affect the chemical balance by ingesting psychedelics, hypnotics, stimulants, or other mood-altering drugs.

Dr. Hobson begins the monograph with a detailed review of consciousness, image transformation in dreams, and a historical perspective. He agrees that understanding dreams is "a key building block of any psychological theory of mental illness…and of great value to the individual seeking to understand the interaction between (mostly) unconscious emotional impulses and (sometimes) conscious cognition." However, he rejects Freud's disguised-censorship hypothesis of dreams, the idea that thwarted instinctual drives are released from repressive control during sleep and have to be disguised in dreams so as not to invade consciousness and disrupt sleep. He finds no scientific support for Freud's theory of dreams. He suggests an alternative explanation—the activation-synthesis hypothesis—that he and McCarley published in 1977 (1): Dreams result from brain activation during sleep. The source of activation is the reticular formation, as it is in the waking state, but the chemical modulation is different: it is cholinergic in REM sleep and serotonergic and noradrenergic in waking. Dr. Hobson also considers another fundamental theme of psychoanalysis—dissociation—and demonstrates how this can be understood in terms of brain anatomy and physiology.

Dr. Hobson goes on to consider the drugstore theme. In a section called "The Medical Drugstore," he compliments the pharmaceutical industry on the development of drugs to treat anxiety, mania, depression, and schizophrenia but points to the risks involved and cautions against indiscriminate use of these agents over the long term.

In the next section, "The Recreational Drugstore," Dr. Hobson opines "recreational drug taking is almost always a response to the human yearning for transcendence," hence the long history of experimentation with psychedelic drugs, narcotics, mushrooms, coca leaves, and the like. Unfortunately, tinkering with the delicate chemical brain balance can lead not only to hyperalertness and ecstasy but also to hallucinations, visions, and psychosis.

The last chapter of the book is devoted to treatment implications and includes a practical guide to what the author calls neurodynamic psychotherapy.

I recommend this book to psychiatrists and all informed lay people who are interested in consciousness, dreams, alien abduction, and drug abuse. The bibliography is scant and there are too few references. However, the book is clear, accessible, and jargon-free. The author speaks to us directly, draws us into his arguments, and—with the help of diagrams, narratives of dreams, illustrations, and tables—is able to make even complicated concepts understandable.

Dr. Backus is clinical associate professor of psychiatry at the University of California, San Diego.