Dreaming— An Altered State of Consciousness

BALTIMORE—Dreaming has been traditionally defined as an unconscious state, in opposition to waking consciousness, but J. Allan Hobson, MD, has put forth an alternate theory. At the 22nd Annual Meeting of the Associated Professional Sleep Societies, Dr. Hobson explained how the unconscious and conscious states might be working cooperatively to the extent that REM sleep dreaming is an altered state of consciousness. Because REM sleep occurs before waking in development, Dr. Hobson suggests that REM sleep dreaming is a protoconscious state which serves as a blueprint for waking consciousness. Not only is this newer theory supported by a physiologic model, but it also has the potential for clinical application.

“We have trouble remembering dreams, and for that reason, we tend to refer to dreaming as unconscious,” said Dr. Hobson, Emeritus Professor of Psychiatry at Harvard Medical School in Boston. “[Sigmund] Freud said that dreaming is the royal road to the unconscious, but what I suggest is that dreaming may be a royal road to consciousness itself.”

A BUILDING BLOCK OF CONSCIOUSNESS

Although dreaming has generally been thought of as an unconscious mental process that merely interacts with consciousness, Dr. Hobson’s theory describes dreaming as a state of consciousness without memory. Dreaming is an ally of waking consciousness, not its enemy, as Freud supposed. This novel approach to studying dreaming has been taken seriously only recently, more than a century after the 1900 publication of Freud’s Interpretation of Dreams presented the traditional framework for thinking about dreaming.

“REM sleep dreaming is a critical conscious state, a state that the brain evolves early in development as a means for preparing itself for waking consciousness,” said Dr. Hobson. “[REM sleep dreaming] develops a sense of self-agency, purpose, movement, sensation, and emotion, and it does all these things in an integrated way. These are the building blocks of waking consciousness. The features of REM sleep dreaming suggest that many aspects of the so-called binding problem of consciousness may be solved automatically before birth.”

Amnesic qualities, a shift in the emotional spectrum, and a general absence of rational thought are among the aspects that typify dreams in contrast with waking. However, although dreams lack logic, Dr. Hobson pointed out, they do possess several traits that parallel aspects of waking consciousness, such as emotional salience and features derived from personal experience. In addition, some aspects of dreaming contain seemingly paradoxic elements. For example, “although we have trouble remembering our dreams, often [they contain] fragments and characters of life experiences that we haven’t thought of for 20 or 30 years,” Dr. Hobson said. “There is something hyperamnesic about this amnesic state.”

Furthermore, Dr. Hobson has found that in waking, external perception is increased and internal perception is decreased, while the exact inverse is true in dreaming. “We’ve found a most extraordinary reciprocity between waking references to thinking and references to internally generated imagery,” he commented. “Waking is characterized by a high proportion of rationality and a low proportion of internally generated perceptions; just the opposite is found in dreaming. This is like a law of psychophysics, in that it is extremely robust.... I think this is a very helpful finding in terms of the notion of dreaming as a protoconscious state that interacts with waking in positive and interesting ways.”

Dr. Hobson has also been examining secondary consciousness, the elements of which—volition, abstraction, sense of purpose, recognizing what something might mean—do not generally appear in dreams. This contrasts with the primordial sense of mere awareness exhibited by primary consciousness, which is present during REM sleep dreaming.

“There are some hints that the brain is trying very hard to come up with solutions [to problems in waking life] while we’re asleep, but it doesn’t do that very well,” he said. “What it does very well is reiterate and reinforce the fundamental building blocks of consciousness.”

THE AIM MODEL

Dr. Hobson has devised a three-dimensional schema, called the AIM model, to use as a framework for understanding the relationship between dreaming and waking on a physiologic level and to represent these states as points in the state space. The model represents three major axes—activation (A), input source (I), and modulation (M)—all of which change as the brain transitions from waking to sleeping to REM sleep dreaming.

Although the I and M axes assist in differentiating between dreaming and waking consciousness, the A axis helps account for the similarities. There are high levels of activation in the brain during REM sleep dreaming and waking consciousness. The second axis of the AIM model, however, refers to the replacement of external information sources with those that are internally generated. As the brain’s sensory input and motor output gates are shut down, internal sources come to the forefront of brain activity.

“The brain is equipped with an internal stimulus generator that is capable of conveying large amounts of information,” Dr. Hobson said. “The scanning hypothesis of dreaming posits that the eyes move in directions that correspond to those visualized in the brain during dreaming. The difference is that in REM sleep the eye movements are entirely automatically generated, not volitionally generated as they may be waking. The upper brain looks at the change in the image that would have existed had the eyes been open. This system operates in waking as well, which is further evidence that dream consciousness is a protoconscious state.”

When input/output gating disconnects the brain from the outside world, the brain’s chemistry is then changed through modulation, the third axis of the AIM model. This axis reflects the mode of information processing by the brain, determined by the actions of aminergic and cholinergic neuromodulators, as they change in ratio during transitions from waking to sleeping to REM sleep dreaming.

“The neurons thought to mediate non-REM and REM sleep are waking system generators,” said Dr. Hobson. “The whole brain is bathed in norepinephrine serotonin in order for us to be awake. We have lost input-output gating and are now aware of the outside world, but we are also processing information differently.”

Dr. Hobson hypothesized that REM sleep serves not only as a building block of consciousness but to reorganize memory, endow it with emotional salience, and integrate the other important cognitive processes that need to be done to keep an individual’s brain in reasonable consilience with its environmental experience.

NARCOLEPSY, EMOTIONS, AND LUCID DREAMING

“What use is this model besides helping us understand normal phenomena?” Dr. Hobson asked. “There has to be a kicker, and of course, there is: In narcolepsy, subjects enter REM directly from waking, and they do this in a dramatic way.”

In a study published in Sleep in 2002, Roar Fosse, PhD, examined possible differences between the emotional experiences during REM sleep in patients with narcolepsy and in healthy persons. Emotions were found more often and were more intense during sleep-onset REM among patients with narcolepsy than in nighttime REM of participants either with or without narcolepsy. Feelings of anxiety and fear had the strongest increase, followed by joy and elation. During sleep-onset REM of patients with narcolepsy, high levels of positive emotions (in particular, joy and elation) were linked to more stable REM sleep.

Patients with narcolepsy also had more intense feelings of anxiety and fear, as well as joy and elation, but less frequent experiences of surprise and anger, than participants without narcolepsy. In addition, positive and negative emotions occurred in a balanced fashion in sleep-onset REM and nighttime REM in patients with narcolepsy. The research team theorized that “changes in REM emotion of [patients with narcolepsy] could reflect the effect of the fundamental pathology of this disorder on neurobiologic systems that support cognitive-emotional functions.”

Another area for study—although one that presents a unique challenge—is the state known as lucid dreaming, when one is caught in limbo between waking and REM dreaming. EEG data collected by Ursula Voss, PhD, suggest that during lucid dreaming the brain stem generates REM sleep dreaming, but the reactivation of certain areas of the cortex enables the person to simultaneously be in a waking state. However, Dr. Hobson stated, lucid dreaming is a very unstable state that is difficult to study, because the subject tends not to remain lucid but rather wakes up or falls back into REM sleep dreaming.

Lucid dreaming is “a hybrid state that features both waking and dreaming consciousness in REM sleep,” Dr. Hobson said. “The next step [for study] will be to put these subjects in a scanner and find out whether there are differences in regional brain activation that correspond” to recent findings on the subject.

Dr. Hobson concluded that “waking consciousness is the highest achievement of evolution. By having waking consciousness, we are able to plan, to give talks, to understand each other, and to achieve enormous cognitive capability. This hasn’t happened by accident, as we don’t learn to be awake after we are born. We have dream consciousness already in place when we are born, and we build on top of it a sense of agency, movement, sensation, and emotion—all the details of individual experience.”

Or, to put it differently, “I don’t have to invent consciousness every time I wake up,” he said. “There is a program in my brain for consciousness, and it needs relatively little adjustment to be brought into contact with reality.”

NR