The Basic Rest Activity Cycle

The fundamental idea for the creation of the model of the basic rest-activity cycle (BRAC) hypothesis was formulated by Kleitman (1963, 1982). He suggested the existence of a rhythm that causes not only cyclical, approximately 90-minute changes in imagination activity during sleep (reflected in the commonly known stages of sleep), but also analogous phenomena during wakeful-ness. Kleitman (1982) cites about 50 articles supporting his hypothesis, including some experimental data supporting it. An approximate 90-minute oscillation was found in—

a. Activity of the imagination during wakefulness—Kripke and Sonnenschein (1978) showed the existence of cyclical (72-120 min) activity of the imagination both in the laboratory and in more natural settings, b. Intensity of visual illusions (Lavie et al., 1975), c. Accuracy of motor coordination (Gopher and Lavie, 1980), d. Time of behavioral reactions (Orretal., 1974), e. Quality of task performance (Sterman, 1985), f. Cognitive styles (Klein and Armitage, 1979).

g. Different records of EEG (Kripke and Sonnenschein, 1978; Geretz and Lavie, 1983; Manseau and Broughton, 1984; Okawa et al., 1984).

An approximately 90-minute periodicity was found in some physiological functions such as renal secretion, gastric motility, cortical alertness, respiratory rate, and heart rate (see Lavie and Kripke, 1981; Lavie, 1985, 1989). Experiments with ultra-short sleep indicate that the REM oscillation, once activated, occurs periodically with a mean inter-REM interval of 96 minutes and continues to function during brief periods of waking (Lavie, 1987).

Erickson and colleagues claim that on applying hypnosis, he and his coworkers observed a tendency for cyclical, approximately 90-minute common, everyday trance occurrence (Erickson et al., 1976; Erickson and Rossi, 1979; Rossi, 1986). They considered the hypnosis as the utilization of the patient's own mental mechanisms.

The idea of combining BRAC activity with the changing domination of brain hemispheres has been presented by various authors (Jouvet, 1973; Van Valen, 1973; Broughton, 1975). Singer (1975) claims that image content of daydreaming is associated with the right hemisphere, and verbal content with the left. There are EEG data obtained during sleep supporting this hypothesis (Goldstein et al., 1972; Rosekind et al., 1979; Hirshkowitz et al., 1980; Herman et al., 1981) Other studies indicate a relation between visual imagery and right hemisphere activity (Short, 1953; Morgan et al., 1971; Davidson and Schwartz, 1976). There are data linking specific right hemisphere EEG activity (alpha blocking mainly) and imagination activity (see Ley, 1983). Werntz et al. (1982) found a correlation between the relative integration of EEG values in one hemisphere with the relative nostril dominance, the so-called nasal cycle. However, periodicity ranged from 25 to greater than 200 minutes. The approximate 90-minute oscillations in cognitive styles, suggesting changes in the balance of hemispheric activity, have also been documented (Klein, and Armitage, 1979). Data indicating that right-hemisphere-related tasks were better performed after awakening from REM rather than from non-REM sleep (Gordon et al., 1982; Bertini et al., 1982; Lavie et al., 1984) support the hypothesis of attributing REM phase, spontaneous dreaming activity to the nondominant hemisphere. Researchers on the so-called split-brain (Sperry, 1964) began a number of theoretical studies on the specificity of brain hemispheric activity suggesting that the left hemisphere is connected with conceptual, logical, linear, and cause-and-effect thinking, while the right hemisphere is responsible for more image-like, pictorial, intuitive, holistic thinking (see Springer, and Deutsch, 1989; Budzynski, 1986). However, according to a careful and comprehensive reconsideration of experimental data on the BRAC (Armitage, Hoffman, and Moffitt, 1992), an unihemispheric model of sleep and potential BRAC should be replaced by a model of the degree of hemispheric synchronization. The oscillations in electrophysiology during sleep and wake-fulness are best described by 80-120-minute rhythms in hemispheric balance, which appear to be continuous throughout sleep and wakefulness and support the BRAC hypothesis. It is suggested that REM-NREM comparisons should be replaced by comparisons between fast-frequency, low-amplitude sleep (FFLA-sleep) and slow-frequency, high-amplitude sleep (SFHA-sleep). These revisions may be easily incorporated into the integrated model of the main states of consciousness. According to them, domination of the right hemisphere activity should be replaced by hemispheric balance, whereas dominance of left-hemisphere activity should be replaced by desynchronization of hemispheric activity; REM sleep, by FFLA sleep; and NREM, by SFHA-sleep. This modification does not change the main ideas about states of consciousness in relaxation presented above.

3.1.1. The Data Against BRAC

The approximate 90-minute rhythmicity characteristic of BRAC was not found in experiments with an activity-recording apparatus carried out by Kripke etal. (1978) and Okudaira et al. (1984). As a result, it was suggested that the concept of a single, basic oscillator particularly related to activity should be revised. The 90-minute rhythmicity was not correlated with REM phase in sleep ina study carried out by Lavie and Kripke (1981). Studies indicating the existence of REM in real time (Globus, 1966) were conducted only on two cases and they were not confirmed by other studies (Dirlich et al., 1977; Mealey and Carman, 1978). Experiments presenting 90-minute oscillation in cognitive styles (Klein and Armitage, 1979) were not replicated (Kripke et al., 1983). This is also true for studies presenting cyclical activity of imagination (Kripke and Sonnenschein, 1978; Kripke et al., 1985).

3.1.2. Why a Hypothesis about Cyclical Activity of Imagination Should Not Yet Be Abandoned

It seems surprising that ultradian studies are nearly ignored by contemporary psychology, whereas results of several physiological researchers suggest that biological rhythms cause changes in states of consciousness. We can find arguments for more precise hypotheses. Data presented as arguments against the BRAC are equivocal and disputable. Results indicating an absence of the BRAC were interpreted as suggesting a "modification rather than rejection of Kleitman's concept" because "there are 90-100-minute periodicities in various other physiologic functions, even if not in activity" (Okudaira, et al., 1984). In the nonreplication of the Klein and Armitage (1979) and Kripke and Sonnenschein (1978) experiments there may be a strong argument against the hypothesis of a biologically determined tendency for changes in states of consciousness. However, all experiments were done with a small number of subjects (8-12) which may have been part of the problem with failure to replicate. Also, contemporary psychology indicates that vividness of imagery is an ability that is differentiated in the population (Marks, 1973), and when imagery vividness is not taken into account, failures to replicate may occur (Wallace, 1990). Moreover, method of the studies on cognitive styles by Kripke et al. (1983) differs from the original in several aspects, one example being the relationship between financial benefit and good task performance. The second experiment by Kripke and Sonnenschein (1978) was not done in the replication studies (Kripke, et al., 1985).

3.1.3. Concept of Protective Mechanisms of the BRAC and Metabolism of Information

The conception of the protective mechanisms of the BRAC explains where the cyclical activity of imagination may be hidden. It seems obvious that in Western Culture natural rhythmicity, if it exists, is suppressed during wakefulness and that spontaneous states of highly vivid imagination are regarded as unusual and abnormal. They thus give rise to fear and hesitancy, which interrupt those states. If we accept the hypothesis that ultradian rhythmicity of imagination is a biological reality, human culture should accommodate it in some way. Natural everyday observations show the occurrence of situations in which people experience states of consciousness with spontaneous vivid imagination and a passive state of mind, not only without fear of anxiety, but with a feeling of rest. Only irrational altered states of consciousness cause fear, whereas rationally explained states may be experienced with pleasure and restfulness.

According to the metabolism of information model, the inflow of information is as necessary to life and the proper functioning of the organism as is the inflow of energy. The amount of information must be maintained within certain limits. An insufficiency of information causes functional distemper in the organism and may even lead to death by making the inflow of energy (nourishment) impossible. An excess of information leads to overload, fatigue, and disturbances in information metabolism which may have consequences similar to those brought about by the insufficiency of information. The sleep-waking rhythm may be connected with proportional changes between the sensitivity threshold for interoceptive and exteroceptive stimuli, whereas the BRAC stems from changes in activity of the cerebral hemispheres and from the cyclic dominance of either the reception of information coming from external sources of stimulation (environment and body) or from internal sources of stimulation. In case of any disruption in the optimal range of inflow of information, we find two main protective mechanisms. Natural Protective Mechanisms of the Metabolism of Information

These mechanisms are characterized, according to the model, by reduction of goal-oriented activity of imagination. This results in a lack of any activity of imagination or in the reorganization of cognitive processes into a culturally acceptable form.

a. In case of a shortage of information, the activity of the imagination grows. The most spectacular supporting data come from experiments of sensory deprivation.

1. "Thoughtlessness" phenomena. This is a specific kind of staring, characterized by cognitive absence, which according to the model presented, may be considered as the intermediate state between ordinary waking states of consciousness (OWSC) and differentiated waking states of consciousness (DWSC) that is a daily analog of REM sleep that lasts for a relatively short time, and for cultural reasons is stopped when spontaneous imagination activity increases. We may suppose that the rest phase of the BRAC reveals itself during this phenomenon and that it promotes some degree of rest.

2. "Physiological manifestations." Rossi (1986) postulates that the rest phase of the BRAC has its own manifestation in different physiological-reaction-like changes—respiratory shift, yawning, hiccuping, burping, or sounds emanating from the gastrointestinal tract, etc.—and in addition during some forms of behavior, such as crossing one's arms or legs, leaning the head or body to one side, wiggling the neck, legs, eye-blinking, etc.

b. In the case of an excess of perceived stimuli, the control center becomes disorganized and the perception is finally disturbed, which leads to a phenomenon analogous to that caused by lack of information. This can be observed mainly in states of overfatigue. Culturally Protective Mechanisms of the Metabolism of Information

The metabolism of information model enables reconsideration of some popular forms of resting as the protective mechanism enabling maintenance of an optimal range of stimulation coming from internal versus external sources and the occurrence of psychophysiological phenomena combined with the rest phase of the BRAC (Kokoszka, 1990a, 1993b).

a. Application of exogenous agents like alcohol, drugs. These agents, through physiological mechanisms, lead to disorganization of information metabolism, goal-oriented activities, and to limitation of the inflow of stimuli from the external sources. Nicotine and caffeine, on the other hand, facilitate occurrence of the "thoughtlessness phenomena" or passive, vivid states of imagination.

b. Relaxation practices like meditation, autogenic training, etc. These may be considered as a means of intentional limitation of information inflow.

c. Application of endogenous agents by means of physical fatigue can lead to disorganization of information metabolism. The feeling of fatigue gives an explanation for nonlogical experiences.

d. Purposeful overstimulation leads to disorganization of information metabolism and seems to be the most popular way to achieve "rationally explained" spontaneous vivid imagination states, including reading a newspaper, listening to the radio, watching television, etc., while tired. Some other popular forms of rest may be considered in terms of these mechanisms, such as sightseeing and aesthetic and sexual experiences.

e. "Take-a-break" periodicity: some authors (Kleitman, 1969; Rossi, 1986) suggest that there is approximately a 90-minute periodicity in cultural customs of taking breaks for tea, lunch, etc. that enables occurrence of the rest phase of the BRAC.

All the situations described above have in common sensations with spontaneous vivid imagination activity accompanied by a relatively passive attitude of mind and an inner acceptance of their irrationality and nonlinear nature by the person experiencing them. The intensity and degree of extraordinariness of experiences in these situations are commonly recognized and culturally accepted. All of them are experienced as form of a rest. The passive state of mind seems to be an essential psychological factor of the rest phase activity states. The protective mechanisms lead to the DWSC. However, we can speculate that the observed data represent a much more complicated psychophysiological phenomena which may mask obvious parameters of DWSC.

The concept of protective mechanisms is congruent with observations leading to a hypothesis of a natural drive for the occurrence of altered states of consciousness, (Weil, 1972), which considers different methods only as means of enabling the expression of an innate tendency. It is compatible with an activation-synthesis hypothesis of dream processes (Hobson and McCarley, 1977), which suggests that the forebrain, which is automatically activated by cyclical brainstem activity, synthesizes the dream by comparing information generated in specific brainstem circuits with information stored in memory. Siegiel et al. (1981) found that the specific cells in the pons (the REM sleep center) also fire in a similar way during wakefulness. In response to these findings, Hobson and McCarley contend that the firing is much greater in REM sleep, and in this respect is different from that of wakefulness (see Horne, 1988). However, according to the BRAC hypothesis, activation of the pontine mechanism may be understood as a source of an increase of spontaneous, vivid, imagination activity during sleep as well as in wakefulness. Spontaneous imagination activity can be considered as an ambiguous material into which the experiencing person is projecting his own expectation (Kokoszka, 1983, 1987-88), or as an effect of unconscious mental activity. More precisely, as was postulated by Hunt (1985), it may be the effect of exteriorization of the deep semantic structures.

3.1.4. Empirical Data Supporting the Protective Mechanisms of the BRAC and of the Information Metabolism

It should be noticed that the concept of the protective mechanisms of the BRAC and information metabolism is compatible with the concepts of the ultradian healing response and the ultradian stress syndrome by Rossi (1991). Moreover, it explains cases when the ultradian healing response does not occur regularly in a 90-minute rhythm and is not accompanied by the ultradian stress syndrome. This syndrome could be considered the result of extreme and prolonged deprivation of the rest phase of the BRAC (i.e., lack of the effective protective mechanisms).

The concept of protective mechanisms received some empirical confirmation recently (Duchniewska and Kokoszka, 2003). In order to verify it, 30 persons (21 women and 9 men) aged between 19 and 52 (M = 29.1; SD = 10.08) answered specially designed sets of questions three times a day (at noon, at 5 p.m., and before sleep) over two consecutive days. All of the examined individuals reported the situations that occurred during the day and that were accompanied by an increase of spontaneous of imagination. Such states had in common the following situations:

• A situation in which one was staring at something while not doing anything in particular—while traveling by different means of transportation (by bus, tram, subway, or car), using the toilet, taking a short rest after physical effort, relaxing in the bathtub or in the shower, lying in bed just before sleep, sunbathing, being at the beautician or hairdresser, standing in a long queue in a shop, waiting for somebody or something (for a bus, an important phone call, or a green light).

• A situation of stretching oneself, walking around the room with an intention of stretching one's legs or yawning that leads to a break in an activity that one has been doing for quite a long time.

• A situation in which one activity has been done for a long period of time: entering data into a computer, washing-up, cleaning the house, washing clothes, ironing, watering flowers, brushing one's teeth, peeling potatoes, different kinds of exercises (aerobics, gym).

• A situation in which a large amount of new data is received: at a meeting in the workplace; a long conversation; activities at school; reading a book, a newspaper, a long letter; watching television; an exhibition in the museum; listening to the radio; learning; looking at pictures or a color magazine.

• A situation of making a physical effort: a long walk, exercising in the gym, aerobics, dancing at a party, a bicycle trip, a basketball game, or sexual activity.

• Having a meal: breakfast, dinner, supper, and small snacks at work (yogurt, a chocolate bar, a sweet bun), smoking cigarettes, drinking coffee or tea, etc.

• Drinking excessive amounts of alcohol.

• Using classical relaxation techniques.

Table 5.1. Frequency of protective mechanisms of information metabolism



Frequency in all

Percentage of


reports (N=573)

all reports

Purposeful overstimulation












Physiological manifestations









The reported situations of an increased spontaneous imagination fall into categories of the main protective mechanisms of information metabolism described by Kokoszka (1990,1993b). Most of them were classified as purposeful overstimulation, thoughtlessness, and tiredness (see Table 5.1.)

The frequency of the protective mechanisms occurrence varied from 6 to 13 times a day (on the first day M = 9.0; SD = 1.5; on the second day M = 8; SD = 1.65). The time span of the situations in which there was a spontaneous increase of activity of imagination wavered from fiveminutes to three hours. A considerable majority of them lasted from five (68%) to ten minutes (19%) (see Table 5.2).

There were considerable differences in phenomenology between the experiences considered by subjects as the most and the least detached from the states of interest in the environment. Whereas only the experience of "having no thoughts" appeared more often (p < .05) in the state of the least detached from the current matters, many experiences were more often reported the most detached ones (see Table 5.3).

The results indicates that states considered as mechanisms of information metabolism were reported by all subject with a mean frequency close to the predicted (approximately 10 cycles, presuming 15-17 hours of wakefulness a day) according to the BRAC. Most often they were classified as purposeful overstimulation, thoughtlessness, and fatigue.

Table 5.2. Length of the protective mechanisms occurrence.

Amount of reported

Percent of reported




5 minutes



10 minutes



15 minutes



20 minutes



30 minutes



1 hour



2 hours



3 hours



Table 5.3. Experiences accompanying states considered by subjects as the most and the least detached from the states of interest in the environment.

Number reports when detachment from reality was—


The deepest

The slightest

Level of significance, p

Uncontrolled feeling of coming light filling the





Being immersed in the emotions of the highest




satisfaction,triumph, grandness, that can be

compared to over-psychological orgasm

Intellectual enlightening that is indescribable




Feeling of transcendental love and compassion




for all the living creatures

The sense of death disappears and there




follows the escalation of physical and

mental activity

Reassessment of things and intensive




experience of the value of beauty

The sense of extraordinary intellectual abilities




The sense of mission




Charismatic changes in personality




The development of unusual skills (e.g.,




telepathy, healing, etc.)

Alernations in thinking




Disturbed time sense




Loss of control




Change in emotional expression




Body image change




Perceptual distortions




Change in meaning of significance




Sense of the ineffable




Feeling of rejuvenation








The feeling of having no thoughts




Being immersed in pleasant, positive feelings




of happiness, joy and peacefulness, etc.

The feeling of being touched by holy strengths




of positive influence

The feeling of identification with somebody





The feeling of absolute peace and stillness




The feeling of sadness




The feeling of overwhelming laziness




The feeling of unity with everyone




Intellectual enlightenment—understanding




The feeling of sacrifice to God


The feeling of being somebody else




high level activity of the right hemisphere predominant reception from internal stimulation sources passive state of mind (contemplation)


spontaneous imagination activity


high activity of hypnogenic lack of control over system content and form of one's experiences high threshold for exteroceptive stimuli weak feedback relation with surroundings


lack of aspiration to rationality of experiences



high control over content and form of one's experiences


strong aspiration to rationality of experiences



high activity of activating system high threshold for interoceptive stimuli strong feedback relation with surroundings goal oriented imagination activity


active state of mind (action)

high level activity of the left hemisphere predominant reception from external stimulation sources

Figure 5.2. An integrated model of the main everyday states of consciousness (Kokoszka, 1990-91).

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