Chapter 4: States of Consciousness
Consciousnessis our awareness of the various cognitive processes that operate in our daily lives: making decisions, remembering, daydreaming, concentrating, reflecting, sleeping, and dreaming, among others. Psychologists divide consciousness into two broad areas: waking consciousness, which includes the thoughts, feelings, and perceptions that arise when we are awake and reasonably alert; and altered states of consciousness (ASC), during which our mental state differs noticeably from normal waking consciousness.
NATURAL VARIATIONS IN CONSCIOUSNESS
To make sense of our complex environment, we choose what to absorb from the myriad happenings around us and filter out the rest. This applies to both external stimuli such as sounds, sights, and smells, and internal sensations such as heat, cold, pressure, and pain. Even our thoughts, memories, emotions, and needs are subjected to this selective process. We also perform familiar tasks, such as signing our names, without deliberate attention. Many psychologists believe that important mental processes go on outside of normal waking consciousness, perhaps as a form of automatic processing.
Daydreaming and Fantasy
Daydreaming occurs without effort, often when we seek to escape the demands of the real world briefly. Some psychologists see no positive or practical value in daydreaming. Others contend that daydreams and fantasies allow us to express and deal with hidden desires without guilt or anxiety. Still others believe that daydreams build cognitive and creative skills that help us survive difficult situationsthat they serve as a useful substitute for reality or a beneficial way of relieving tension. Finally there are those who view daydreaming as a mechanism for processing the vast array of information we take in during the day, enabling us to retrieve thoughts put aside for later review and to transform them into new and more useful forms.
Sleep and Dreaming
Research into sleep patterns shows that normal sleep consists of several stages. Following the initial "twilight" state, which is characterized by irregular, low-voltage alpha waves and a state of relaxed wakefulness, the sleeper enters Stage 1 of sleep. This stage, which is marked by a slowing of the pulse, muscle relaxation, and side-to-side rolling movements of the eyes, lasts only a few moments. The sleeper is easily awakened from Stage 1 sleep.
Stages 2 and 3 are characterized by progressively deeper sleep. In these stages, the sleeper is hard to awaken and does not respond to noise or light. Heart rate, blood pressure, and temperature continue to drop.
During Stage 4 sleep, when the brain emits very slow delta waves, heart and breathing rates, blood pressure, and body temperature are as low as they will get during the night. About an hour after first falling asleep, the sleeper begins to ascend through the stages back to Stage 1a process that takes about 40 minutes. At this stage in the sleep cycle, heart rate and blood pressure increase, the muscles become more relaxed than at any other time in the cycle, and the eyes move rapidly under closed eyelids. It is this rapid eye movement (REM) that gives this stage of sleep its name.
REM sleep is also called paradoxical sleep because while brain activity and other physiological symptoms resemble those recorded during waking consciousness, the sleeper appears to be deeply asleep and is incapable of moving because of paralysis of the body's voluntary muscles. Non-REM, or NREM sleep, refers to the non-rapid-eye-movement stages of sleep that alternate with REM stages during the sleep cycle.
Dreams are visual or auditory experiences that occur primarily during REM periods of sleep. Less vivid experiences that resemble conscious thinking tend to occur during NREM sleep. One theory to explain why REM dreams are so vivid cites the level of brain arousal during REM sleep. The brain's activity closely resembles that of normal waking consciousness, but because of its relative insensitivity to outside sensory input, it draws on nothing but internal images from memory.
Several theories have been developed to explain the nature and content of dreams. According to Freud, dreams have two kinds of contents: manifest (the surface content of the dream itself) and latent (the disguised, unconscious meaning of the dream). One recent hypothesis suggests that dreams arise out of the mind's reprocessing of information absorbed during the dayinformation that is important to the survival of the organism. Thus, dreaming strengthens our memories of important information. At the neurophysiological level, REM sleep may be related to brain "restoration" and growth. If people are deprived of REM sleep, they often become anxious, irritable, and testy, and, when they are permitted to have REM sleep again, the amount of REM they experience almost doublesan effect referred to as REM rebound.
Other phenomena associated with sleep and dreaming include sleepwalking, sleeptalking, sleep terrors, nightmares, and sleep learning. Most episodes of sleeptalking and sleepwalking occur during delta sleep. Unlike nightmares, sleep terrors, which are more common among children than adults, prove difficult to be awakened from, and are rarely remembered the next morning. The learning of complex material during sleep has never been scientifically confirmed.
Sleep deprivation is a major problem in the United States. Inadequate sleep has been shown to adversely affect attention, memory, reaction time, judgment, and job performance. Moreover it is implicated as one of the major causes of automobile accidents.
Many people are afflicted by sleep disorders. Insomnia is characterized by difficulty in falling asleep or remaining asleep throughout the night. Apnea is marked by breathing difficulties during the night and feelings of exhaustion during the day. Narcolepsy is a hereditary sleep disorder characterized by sudden nodding off during the day and sudden loss of muscle tone following moments of emotional excitement.
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