Consciousness
Consciousness is the awareness we have of ourselves and our environment. Different states of consciousness are associated with different patterns of brain waves. Brain waves are tracings of electrical activity that is going on in the brain. Scientists record brain waves using an electroencephalograph (EEG), which monitors electrical activity through electrodes placed on the scalp. There are four main types of brain waves: alpha, beta, theta, and delta.
Type of Brain Wave Alpha Beta Theta Delta
Corresponding Mental State Very relaxed or meditating Awake and alert Lightly asleep Deeply asleep
Sleep Sleep is just one of many types of consciousness we experience, and sleep itself comprises several states of consciousness. Even when we’re sleeping, our brains and bodies continue to work.
Biological Rhythms Sleep is affected by biological rhythms or periodic physiological changes. Biological rhythms are regular, periodic changes in a body’s functioning. There are three types of biological rhythms: •
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Circadian rhythms: biological cycles that occur about every twenty-four hours. Sleep follows a circadian rhythm. Hormone secretion, blood pressure, body temperature, and urine production also have circadian rhythms. Infradian rhythms: biological cycles that take longer than twenty-four hours. For example, women’s menstrual cycles occur about every twenty-eight days. Ultradian rhythms: biological cycles that occur more than once a day. Sleep follows an ultradian rhythm of about ninety minutes as well as a circadian rhythm. Alertness and hormone levels also follow ultradian rhythms.
Biological rhythms usually synchronize with environmental events such as changes in daylight. However, experiments have shown that many biological rhythms continue to have the same cycle even without cues from the environment. Such biological rhythms are endogenous, which means that they originate from inside the body rather than depend on outside cues.
Biological Clocks Endogenous rhythms exist because the body has biological clocks that keep time. Biological clocks can be adjusted by environmental cues, such as changes in temperature. In humans, the suprachiasmatic nucleus (SCN) is the main biological clock that regulates circadian rhythms of sleep. The SCN lies in the brain’s hypothalamus. When light stimulates receptors in the retina of the eye, the receptors send signals to the SCN. The SCN then sends signals to the nearby pineal gland, which secretes melatonin, a hormone that regulates the sleep cycle.
Jet Lag Jet lag is the fatigue and disorientation air travelers feel after a long flight. Although traveling itself drains energy, the time change also contributes to fatigue. People experience jet lag when the events in their environment are out of sync with their biological clocks. Example: A traveler leaves New York City at eight in the morning and arrives in London about seven hours later. For her, it’s three in the afternoon, but because of the time change, in London it’s eight in the evening. Her body, thinking it’s mid-afternoon, will be confused by the lack of sunlight, and she’ll experience jet lag.
The Function of Sleep Although everyone sleeps, no one really knows why people sleep. Researchers have proposed several theories to explain how sleep evolved to be a necessary behavior: • • •
People conserve energy by sleeping periodically. Sleep has a protective function, as it keeps people tucked away at night, safe from predators. Sleep restores body tissues that are depleted during daily activities.
Sleep Research Sleep research has provided a lot of information about what happens to the brain and body during sleep. Researchers study sleep by monitoring subjects who spend the night in labs, and they use various instruments for different purposes: • • • •
Electroencephalographs (EEGs): record brain waves Electromyographs (EMGs): record muscle activity Electrooculographs (EOGs): record eye movements Electrocardiographs (EKGs): record the activity of the heart
Other instruments monitor breathing, body temperature, and pulse.
Sleep Stages During one night’s sleep, people pass through several cycles of sleep, each lasting about ninety to one hundred minutes. There are five distinct stages of sleep in each cycle: 1, 2, 3, 4, and REM.
Stages 1–4 When people are relaxed and ready to fall asleep, their EEG will show mostly alpha waves. When people fall asleep, they enter into stage 1 sleep, which lasts just a few minutes. In stage 1, the EEG shows mostly theta waves. Heart rate, breathing rate, and body temperature drop, and muscles relax. Fantasies or bizarre images may float around in the mind. After a few minutes of stage 1 sleep, people move into stage 2 sleep. Stage 2 lasts about twenty minutes and is characterized by short bursts of brain waves called sleep spindles. People then pass into slow-wave sleep, which occurs during stages 3 and 4. In stages 3 and 4, which together last about thirty minutes, the EEG displays mostly delta waves. People in stage 3 and 4 sleep show slow breathing and pulse rates, have limp muscles, and are difficult to rouse. Sleepwalking Most people in stage 4 sleep are still, quiet, and difficult to rouse. Sleepwalkers, however, sometimes become physically active during stage 4. They may get up and walk around their room or even carry on a conversation, take a bath, cook, or go outside and get in their car. Because they are in a deep sleep, most sleepwalkers remember nothing of their actions when they wake up.
REM Sleep At the end of stage 4, people go back through the stages in reverse, from stage 4 to 3 to 2 to 1. When they reach stage 1, instead of waking up, people go into REM, or rapid eye movement, sleep. A single cycle might look like this: 1
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REM
REM sleep is a stage of deep sleep in which, paradoxically, brain wave activity resembles that of an alert person. REM sleep is also called paradoxical sleep. During REM sleep, pulse rate and breathing become irregular, eyes move rapidly under closed lids, and muscles remain very relaxed. Genital arousal also happens during REM. In women, the clitoris becomes swollen with blood, and vaginal lubrication increases. In men, the penis becomes erect. EEGs show mostly beta waves during REM sleep. Although dreaming happens in other sleep stages as well, dreams are most vivid and frequent during REM sleep. People typically go through about four sleep cycles during one night of sleep. The REM stage of sleep gets longer and longer as the night passes, while stage 3 and 4 sleep gets shorter and shorter. During the night’s first sleep cycle, the REM stage lasts about ten minutes. During the night’s last sleep cycle, people may spend about forty to sixty minutes in REM sleep. Non-REM sleep becomes more shallow as the night goes on, and eventually the sleeper awakens.
Sleep Deprivation Different people need different amounts of sleep. Some people can function with fewer than six hours of sleep a night, while others can’t manage without at least nine hours. Research shows that getting insufficient sleep can have negative effects on health, productivity, and performance. Researchers have also studied the effects of insufficient REM sleep. Experiment subjects who are intentionally deprived of REM sleep tend to enter the REM stage of sleep more and more frequently during the night. After an REM-deprivation experiment has ended, subjects usually experience a REM rebound effect, spending more time in the REM stage on subsequent nights to make up for lost REM time.
Aging and Sleep Sleep patterns change as people get older. Newborn babies spend about two-thirds of their time in sleep. As people age, they tend to sleep less. The amount of time spent in REM sleep also changes over time. In very young babies, about half of all sleep is REM sleep. As babies get older, the proportion of REM sleep decreases.
Sleep Disorders Everyone has occasional difficulty sleeping, but some people have insomnia, a chronic problem with falling or staying asleep. Another kind of sleep disorder is narcolepsy, which is a tendency to fall asleep periodically during the day. Narcolepsy can be dangerous, as people who experience it may fall asleep while driving or operating machinery. Sleep apnea is another condition that can have negative effects on health and safety. People who have sleep apnea stop breathing many times during a night’s sleep, and each time they stop breathing, they wake up briefly and gasp for air. This prevents them from getting enough deep sleep, which leads to irritability and sleepiness during the day. Chronic sleep apnea can also result in high blood pressure.
Dreams The function of dreams is as much a mystery as the function of sleep.
Freud’s Dream Theory Psychoanalyst Sigmund Freud believed that dreams allow people to express unconscious wishes they find unacceptable in real life. He drew a distinction between the manifest content and the latent content of dreams. The manifest content is the plot of the dream: who’s in the dream, what happens, and so on. The latent content is the dream’s hidden meaning. According to Freud, the manifest content is a symbolic representation of the latent content. In other words, the plot acts as a disguise that masks the real meaning of the dream. Cigars and Tunnels Freud theorized that many psychological problems stem from repressed sexual urges. In his dream theory, certain objects symbolize sex or genitals. The most famous Freudian symbol is the cigar, which, owing to its shape and association with men, usually represents a penis. Freudian psychiatrists would interpret tunnels and caves as vaginas.
Activation-Synthesis Theory Another theory, called the activation-synthesis theory, proposes that neurons in the brain randomly activate during REM sleep. Dreams arise when the cortex of the brain tries to make meaning out of these random neural impulses. According to activationsynthesis theory, dreams are basically brain sparks.
Problem-Solving Dreams Some researchers think that dreams express people’s most pressing concerns and might help to solve problems in day-to-day life. If someone has an important job interview coming up, for example, he may rehearse scenarios for the interview in his dreams. If someone has relationship difficulties with a significant other, his dreams may give him clues to help solve the problem.
Neural Housekeeping Some theories argue that dreams arise during the brain’s routine housekeeping functions, such as eliminating or strengthening neural connections. Dreams, then, are a way of cleaning up brain files. During lucid dreams, people are aware that they are dreaming and may be able to control their actions to some extent within the dream.
A nightmare is an elaborate dream sequence that produces a high level of anxiety or fear for the dreamer. The dreamer may experience a sense of physical danger to himself, or his loved ones, or a strong sense of embarrassment about doing something unacceptable. These dreams are vivid and can often be elaborately described by the dreamer upon awakening; they generally occur during REM sleep. In contrast, night terrors occur in much deeper sleep states; these involve behaviors such as screaming, crying, and jerking/lunging movements while asleep.
Altered States Some states of consciousness don’t occur naturally and must be induced in some way. These include hypnotic states, meditative states, and drug-induced states.
Hypnosis Hypnosis is a procedure that opens people to the power of suggestion. A hypnotist puts a subject in an altered state by encouraging relaxation and sleepiness and often describing the sorts of physical sensations a subject should be feeling. Once a subject is in the altered state, he or she may act, perceive, think, or feel according to the hypnotist’s suggestions. Not everyone can be hypnotized, and some people are more hypnotizable than others. The following chart shows what hypnosis can and can’t do. Hypnosis can: Cause people to be relaxed, have a narrowed focus of attention, and be highly engaged in fantasies Produce anesthesia and treat a range of psychological and medical problems Cause hallucinations and distortions in sensory perception Reduce inhibitions Cause changes in behavior after the hypnosis has ended
Hypnosis can’t: Work equally effectively for everyone Force people to do things against their will Make people act in ways that would normally be beyond their physical or mental abilities Reliably increase the accuracy of memories Allow people to actually reexperience past events or lives
If hypnotized people are instructed to forget what happened during hypnosis, they later claim to have no memory of it. This phenomenon is called posthypnotic amnesia. A hypnotic state isn’t sleep—brain waves, for example, do not reliably change during hypnosis as they do during sleep. Researchers don’t even agree that hypnosis is an altered state of consciousness. Researchers propose two main theories about hypnosis: •
Ernest Hilgard proposed that hypnosis causes people to dissociate or divide their consciousness into two parts. One part responds to the outside world, and the other part observes but doesn’t participate. According to this theory, hypnosis can make people not react to pain because hypnosis separates the part of
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consciousness that registers pain from the part of consciousness that communicates with the outside world. Many other researchers, such as Theodore Barber and Nicholas Spanos, think hypnosis happens when a suggestible person plays the role of a hypnotized person. According to this theory, hypnotized people simply behave as they think they are expected to.
Meditation Meditation is the practice of focusing attention. People meditate to enhance awareness and gain more control of physical and mental processes. Techniques used in meditation vary and include activities such as repetitive chanting and breathing exercises. Meditative states are associated with an increase in alpha and theta brain waves, and physical indicators of relaxation such as slowed pulse and breathing. Some researchers have found that meditation has long-term effects such as improving physical and mental health and reducing stress. However, researchers disagree about whether meditative states are unique states of consciousness. Some researchers believe relaxation techniques can produce the same kind of state produced by meditation.
Psychoactive Drugs Psychoactive drugs, as opposed to medicinal drugs, have psychological effects, meaning that they change sensory experience, perception, mood, thinking, and behavior. Psychoactive drugs are sometimes called recreational drugs, though some have legitimate medical uses.
Types of Recreational Drugs Researchers usually classify recreational drugs into four types: stimulants, sedatives, narcotics, and hallucinogens. • • • •
Stimulants: drugs that stimulate the central nervous system Sedatives: drugs that slow down the central nervous system Narcotics: also called opiates; drugs that can relieve pain Hallucinogens: drugs that cause sensory and perceptual distortions
Drugs derived from the cannabis plant, such as marijuana and hashish, have features of more than one of these drug types, so researchers sometimes consider cannabis to be a separate, fifth drug type.
Drug type Stimulants
Examples Nicotine, caffeine, cocaine, amphetamines, crystal meth
Sedatives
Alcohol, Valium, Xanax, barbiturates, such as Seconal
Narcotics
Morphine, heroin, opium, codeine, hydrocodone, such as Vicodin
Hallucinogens
LSD, mescaline, psilocybin
Cannabis
Marijuana, hashish
Effects Increased alertness and energy, excitation, euphoria, confidence
Negative effects Anxiety, restlessness, irritability, sleeplessness, paranoia, increased aggressiveness, feelings of panic Euphoria, Impaired relaxation, less coordination, anxiety depression, lethargy, drowsiness, mood swings Euphoria, Lethargy, relaxation, less drowsiness, nausea, anxiety, less impaired sensitivity to pain coordinated, constipation Euphoria, changed Nausea, paranoia, perception, anxiety, feelings of hallucinations, panic, mood swings, insightful moments impaired judgment, jumbled thoughts Euphoria, Sluggishness, relaxation, increased anxiety, impaired awareness, changed memory perception
How Psychoactive Drugs Work Psychoactive drugs work by affecting neurotransmitter function. A single drug can affect the function of more than one neurotransmitter. Drugs can: • • •
Cause more or less of a neurotransmitter to be released at synapses Block reuptake of a neurotransmitter by presynaptic cells Stimulate or block neurotransmitter receptors on postsynaptic cells
Hallucinations Hallucinations are sensory or perceptual experiences that happen without any external stimulus. Hallucinogenic drugs fool the brain into perceiving sights, sounds, and tastes that aren’t actually present, and they may confuse a person’s sense of space and time. For example, a man who takes a hallucinogenic drug may hear voices in his head.
Influences on Psychoactive Drug Effects A given drug doesn’t always have the same effect. If ten people drink beer one evening, they all may have different experiences. The effect of a drug depends on many different factors: • • • • • • • •
The amount of the drug The potency of the drug How the drug is administered How much previous experience a user has with the drug The user’s age and body weight The user’s mood, personality, and motivation The environment in which the drug is used The user’s expectations about the drug’s effects
Chronic Use of Psychoactive Drugs When people regularly use a drug, they may develop a tolerance to it. As time goes on, people with a tolerance need more and more of the drug to get the same effect. When people stop using a drug after a long period of regular use, they often experience withdrawal symptoms. Different drugs produce different kinds of withdrawal symptoms. Not all drugs are addictive. With chronic use, people can get physically or psychologically dependent on a drug. Physical dependence happens when a person must take the drug to avoid withdrawal symptoms. Psychological dependence is when a person keeps taking the drug because of cravings. A drug can be both physically and psychologically addictive. Drug use can be dangerous for several reasons. Heavy or frequent use of drugs can damage body tissues and organs. Overdoses of some drugs, including sedatives, stimulants, and narcotics, can be lethal. Drugs can have dangerous indirect effects by causing people to behave in risky, accident-prone, or unhealthy ways.