Post on 25-Dec-2015
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4th Edition
States of Consciousness
Chapter 4
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What Is Consciousness
• Consciousness is personal awareness of feelings, sensations, and thoughts.
• Changes from normal consciousness are known as altered states of consciousness.
• One common change in consciousness is daydreaming.
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The Rhythms of Life
• A number of biological processes follow regular rhythms or cycles that vary in length.
• The study of biological rhythms, chronobiology, includes research on the effects of such cycles on the diagnosis and treatment of diseases.
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The Rhythms of Life
• Circadian rhythms are biological changes that occur on a daily schedule, including the sleep-wake cycle and the body temperature cycle.
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The Rhythms of Life
• Circadian rhythms are controlled by the suprachiasmatic nucleus (SCN) which is located in the hypothalamus and acts as an internal clock.
• Levels of a hormone secreted by the pineal gland, melatonin, are affected by light and darkness; thus melatonin may play a role in controlling biological rhythms.
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The Rhythms of Life
• By isolating volunteers in an environment without time cues, researchers have found the free-running sleep-wake cycle extends to about 25 hours.
• To correspond to the 24-hour day, the cycle must be reset every day by external cues, especially sunlight.
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The Rhythms of Life
• Jet travel and shift work can disrupt the sleep-wake cycle.
• The symptoms of Jet leg result from the difference between our internal clock and the time in our environment.
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The Rhythms of Life
• It is easier to adapt to phase delays (east-west travel) than to phase advances (west-east travel).
• Rotating shifts can be improved by using a clockwise rotation (days to evenings to nights), which involves a series of phase delays.
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The Study of Sleep
• The major breakthrough in the study of sleep was the observation of rapid eye movements (REM).
• Measures of physiological processes such as the electroencephalograph (EEG) also aid sleep research.
• A sleep cycle lasts approximately 90 minutes and starts with non-REM (NREM) sleep.
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The Study of Sleep
• We descend through NREM Stages I to 4 and then ascend through them to rapid eye movement (REM) sleep.
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The Study of Sleep
• The average adult repeats this cycle about four to six times each night.
• Sleep decreases from about 16 hours at birth to about 7 to 8 hours in young adulthood, with little change thereafter.
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The Study of Sleep
• Observations of sleeping people suggest that many people are not getting enough sleep.
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The Study of Sleep
• Sleep efficiency (time in bed actually asleep) is lower among elderly people, who experience less slow-wave sleep and spend increased time in the lighter stages of sleep.
• Naps are more common than many people believe.
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The Study of Sleep
• Sleep-deprived persons experience microsleeps, which can cause poor performance on tasks requiring attention.
• REM sleep deprivation leads to the REM rebound, an increase in the amount of REM sleep.
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The Study of Sleep
• Infants spend about 50% of their sleep in REM, perhaps to provide stimulation needed for brain development.
• Sleep may have evolved to fill time, but the amount of sleep in each species depends on vulnerability to predators and the need to find food.
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The Study of Sleep
• Most cases of insomnia are of short duration.
• Sleeping pills have limited usefulness and should be used with care.
• The stimulus control method is an effective treatment for sleep onset insomnia.
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The Study of Sleep
• Hypersomnias are sleep disorders marked by excessive daytime sleepiness.
• Narcolepsy is characterized by daytime sleepiness, cataplexy, and other symptoms consistent with the intrusion of REM sleep into waking hours.
• Overweight, middle-aged men are susceptible to sleep apnea, which consists of frequent pauses in breathing during the night.
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The Study of Sleep
• Parasomnias are sleep disturbances other than insomnia and hypersomnias.
• Enuresis (bedwetting) is a common disorder in childhood that can be treated with the urine alarm.
• Sleepwalking and sleep terrors are associated with Stage 4 sleep, tend to occur in children, and usually disappear without treatment.
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The Study of Sleep
• REM sleep behavior disorder occurs in older men and consists of aggressive actions during REM sleep.
• Nightmares are bad dreams that occur during REM sleep.
• Sudden Infant death syndrome (SIDS) is the leading cause of death among infants between 1 month and 1 year of age.
• Placing infants to sleep on the back may reduce the incidence of SIDS.
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The Study of Sleep
• As typically defined, dreams are associated with REM sleep, although N REM sleep is not a mental void.
• Freud suggested that dreams serve to fulfill sexual and aggressive wishes and that we forget dreams due to repression.
• Analysis of the manifest content of a dream yields the dream's latent content, or supposed true meaning.
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The Study of Sleep
• Research has not supported Freud's views on dreams.
• For example, forgetting dreams seems better explained by waking activities that can interfere with recall of dreams than by repression.
• Dreams often reflect cultural characteristics such as a focus on relationships and levels of aggression in a culture.
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The Study of Sleep
• The activation-synthesis hypothesis suggests that dreams result from attempts by the brain to make sense of high levels of neuronal activity.
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Altering Consciousness With Drugs
• Psychoactive substances are drugs that affect consciousness, perception, mood, and behavior.
• Regular and excessive use can lead to substance abuse or substance dependence.
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Altering Consciousness With Drugs
• Alcohol use is associated with a range of medical and psychological consequences.
• One major effect is on parts of the brain responsible for inhibiting behavior.
• The effects of alcohol are related to blood alcohol concentration (BAC), an indication of the amount of alcohol in the blood.
• Your BAC is determined by how much you drink, the time you take to drink it, your weight, and whether you have consumed food before or while drinking.
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Altering Consciousness With Drugs
• Expectations about the effects of alcohol can influence drinking patterns.
• The relation of alcohol to violence, however, seems to be due to its biological effects, not to expectations.
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Altering Consciousness With Drugs
• The rate of alcohol abuse and dependence is higher in men than in women.
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Altering Consciousness With Drugs
• Like alcohol, barbiturates and benzodiazepines are depressants that slow the activity of the central nervous system.
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Altering Consciousness With Drugs
• Stimulants such as amphetamines speed up the activity of the nervous system.
• One of the most widely used stimulants is caffeine, which is found in foods such as chocolate and beverages such as coffee.
• Nicotine, a major component of tobacco smoke, is associated with preventable diseases such as heart disease.
• Cocaine can get to the brain quickly and cause a powerful high followed by a dramatic low.
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Altering Consciousness With Drugs
• Opiates, such as morphine and codeine, are derived from the seedpod of the poppy plant; their primary medical use is to reduce pain.
• Heroin is a semi-synthetic compound derived from morphine.
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Altering Consciousness With Drugs
• Hallucinogens can cause changes in perception, including hallucinations.
• Among the best-known hallucinogens are lysergic acid diethylamide (LSD) and phencyclidine piperidine (PCP).
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Altering Consciousness With Drugs
• Marijuana consists of dried leaves and flowers from the Cannabis sativa plant.
• The active psychoactive ingredient in marijuana is delta-9-tetrahydrocannabinol (THC).
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Altering Consciousness With Drugs
• MDMA or ecstasy is one of the designer drugs that is manufactured from readily available ingredients.
• There is growing evidence that MDMA can have dramatic effects on memory and attention.
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Hypnosis
• Hypnosis, a heightened state of suggestibility, can be traced to the 18th century, when Franz Anton Mesmer claimed he had the power to induce magnetic equilibrium in the bodies of his patients.
• In contrast to the popular view that hypnosis is an altered state of consciousness, evidence suggests it does not differ from a state of relaxation.
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Hypnosis
• Hypnosis has been used to reduce pain in various kinds of medical treatments.
• It is not clear, however, what aspect of hypnosis may be responsible for pain reduction; relaxation, distraction, and expectations seem to play significant roles.
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Hypnosis
• Hypnosis has been used to improve recall.
• However, hypnotically refreshed memories tend to contain distortions and false reports.
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Hypnosis
• In hypnotic age regression, a hypnotized person appears to return to childhood or perhaps even to past lives.
• Research indicates age regression results in the reporting of fantasies or memories suggested by the hypnotist.
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Hypnosis
• The cognitive-social explanation suggests that the observed phenomena can be explained by the relationship between the hypnotist and the hypnotized person, as well as by widely shared expectations about the procedure.
• Another explanation, offered by Ernest Hilgard, suggests that dissociation, or a splitting of consciousness, may be at work in hypnosis.