A painting shows two children sleeping.
Figure 4.1 Sleep, which we all experience, is a quiet and mysterious pause in our daily lives. Two sleeping children are depicted in this 1895 oil painting titled Zwei schlafende Mädchen auf der Ofenbank, which translates as “two sleeping girls on the stove,” by Swiss painter Albert Anker.

Chapter Outline

Our lives involve regular, dramatic changes in the degree to which we are aware of our surroundings and our internal states. While awake, we feel alert and aware of the many important things going on around us. Our experiences change dramatically while we are in deep sleep and once again when we are dreaming. Some people also experience altered states of consciousness through meditation, hypnosis, or alcohol and other drugs.

This chapter will discuss states of consciousness with a particular emphasis on sleep. The different stages of sleep will be identified, and sleep disorders will be described. The chapter will close with discussions of altered states of consciousness produced by psychoactive drugs, hypnosis, and meditation.


alpha wave
type of brain wave characteristic during the early part of NREM stage 1 sleep, which has fairly low amplitude and a frequency of 8–12 Hz
beta wave
type of brain wave characteristic during wakefulness, which has a very low amplitude and a frequency of 13–30 Hz
biological rhythm
internal cycle of biological activity
lack of muscle tone or muscle weakness, and in some cases complete paralysis of the voluntary muscles
central sleep apnea
sleep disorder with periods of interrupted breathing due to a disruption in signals sent from the brain that regulate breathing
circadian rhythm
biological rhythm that occurs over approximately 24 hours
opiate with relatively low potency often prescribed for minor pain
cognitive-behavioral therapy
psychotherapy that focuses on cognitive processes and problem behaviors that is sometimes used to treat sleep disorders such as insomnia
collective unconscious
theoretical repository of information shared by all people across cultures, as described by Carl Jung
awareness of internal and external stimuli
continuous positive airway pressure (CPAP)
device used to treat sleep apnea; includes a mask that fits over the sleeper’s nose and mouth, which is connected to a pump that pumps air into the person’s airways, forcing them to remain open
delta wave
type of brain wave characteristic during stage 3 NREM sleep, which has a high amplitude and low frequency of less than 3 Hz
drug that tends to suppress central nervous system activity
euphoric high
feelings of intense elation and pleasure from drug use
evolutionary psychology
discipline that studies how universal patterns of behavior and cognitive processes have evolved over time as a result of natural selection
one of a class of drugs that results in profound alterations in sensory and perceptual experiences, often with vivid hallucinations
tendency to maintain a balance, or optimal level, within a biological system
state of extreme self-focus and attention in which minimal attention is given to external stimuli
consistent difficulty in falling or staying asleep for at least three nights a week over a month’s time
jet lag
collection of symptoms brought on by travel from one time zone to another that results from the mismatch between our internal circadian cycles and our environment
very high amplitude pattern of brain activity associated with stage 2 sleep that may occur in response to environmental stimuli
latent content
hidden meaning of a dream, per Sigmund Freud’s view of the function of dreams
lucid dream
people become aware that they are dreaming and can control the dream’s content
manifest content
storyline of events that occur during a dream, per Sigmund Freud’s view of the function of dreams
clearing the mind in order to achieve a state of relaxed awareness and focus
hormone secreted by the endocrine gland that serves as an important regulator of the sleep-wake cycle
study that combines the results of several related studies
synthetic opioid that is less euphorigenic than heroin and similar drugs; used to manage withdrawal symptoms in opiate users
methadone clinic
uses methadone to treat withdrawal symptoms in opiate users
type of amphetamine that can be made from pseudoephedrine, an over-the-counter drug; widely manufactured and abused
sleep disorder in which the sufferer cannot resist falling to sleep at inopportune times
night terror
sleep disorder in which the sleeper experiences a sense of panic and may scream or attempt to escape from the immediate environment
non-REM (NREM)
period of sleep outside periods of rapid eye movement (REM) sleep
obstructive sleep apnea
sleep disorder defined by episodes when breathing stops during sleep as a result of blockage of the airway
one of a category of drugs that has strong analgesic properties; opiates are produced from the resin of the opium poppy; includes heroin, morphine, methadone, and codeine
one of a group of sleep disorders characterized by unwanted, disruptive motor activity and/or experiences during sleep
physical dependence
changes in normal bodily functions that cause a drug user to experience withdrawal symptoms upon cessation of use
pineal gland
endocrine structure located inside the brain that releases melatonin
psychological dependence
emotional, rather than a physical, need for a drug which may be used to relieve psychological distress
rapid eye movement (REM) sleep
period of sleep characterized by brain waves very similar to those during wakefulness and by darting movements of the eyes under closed eyelids
REM sleep behavior disorder (RBD)
sleep disorder in which the muscle paralysis associated with the REM sleep phase does not occur; sleepers have high levels of physical activity during REM sleep, especially during disturbing dreams
restless leg syndrome
sleep disorder in which the sufferer has uncomfortable sensations in the legs when trying to fall asleep that are relieved by moving the legs
rotating shift work
work schedule that changes from early to late on a daily or weekly basis
state marked by relatively low levels of physical activity and reduced sensory awareness that is distinct from periods of rest that occur during wakefulness
sleep apnea
sleep disorder defined by episodes during which breathing stops during sleep
sleep debt
result of insufficient sleep on a chronic basis
sleep rebound
sleep-deprived individuals will experience shorter sleep latencies during subsequent opportunities for sleep
sleep regulation
brain’s control of switching between sleep and wakefulness as well as coordinating this cycle with the outside world
sleep spindle
rapid burst of high frequency brain waves during stage 2 sleep that may be important for learning and memory
(also, somnambulism) sleep disorder in which the sleeper engages in relatively complex behaviors
stage 1 sleep
first stage of sleep; transitional phase that occurs between wakefulness and sleep; the period during which a person drifts off to sleep
stage 2 sleep
second stage of sleep; the body goes into deep relaxation; characterized by the appearance of sleep spindles
stage 3 sleep
third stage of sleep; deep sleep characterized by low frequency, high amplitude delta waves
drug that tends to increase overall levels of neural activity; includes caffeine, nicotine, amphetamines, and cocaine
sudden infant death syndrome (SIDS)
infant (one year old or younger) with no apparent medical condition suddenly dies during sleep
suprachiasmatic nucleus (SCN)
area of the hypothalamus in which the body’s biological clock is located
theta wave
type of brain wave characteristic of the end of stage 1 NREM sleep, which has a moderately low amplitude and a frequency of 4–7 Hz
state of requiring increasing quantities of the drug to gain the desired effect
characterized by high levels of sensory awareness, thought, and behavior
variety of negative symptoms experienced when drug use is discontinued