35 Chapter 4. Key Terms

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

cataplexy
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

cognitive-behavioral therapy (CBT)
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

consciousness
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

depressants
a class of drugs that slow down the body’s physiological and mental processes

entheogen
psychoactive substance used to produce an altered sense of consciousness for religious purposes

euphoria
an intense feeling of pleasure, excitement or happiness.

evolutionary psychology
discipline that studies how universal patterns of behavior and cognitive processes have evolved over time as a result of natural selection

hallucinogens
substances that, when ingested, alter a person’s perceptions, often by creating hallucinations (perceptions that are not based on environmental stimuli) or distorting their perceptions of time.

homeostasis
tendency to maintain a balance, or optimal level, within a biological system

hypnosis
state of extreme self-focus and attention in which minimal attention is given to external stimuli

hypnotherapy
use of hypnotic techniques such as relaxation and suggestion to help engineer desirable change such as lower pain or quitting smoking

insomnia
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

K-complex
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

meditation
learning to regulate attentional processes to achieve a sense of wellbeing and peace

melatonin
hormone secreted by the pineal gland that serves as an important regulator of the sleep-wake cycle

meta-analysis
study that combines the results of several related studies

narcolepsy
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

parasomnia
one of a group of sleep disorders characterized by unwanted, disruptive motor activity and/or experiences during sleep

pineal gland
endocrine structure located inside the brain that releases melatonin

psychedelics
also known as hallucinogens, are a class of psychoactive substances that induce profound alterations in perception, thoughts, and emotions

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

sleep
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

sleepwalking
(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

stimulants
a class of drugs that speed up the body’s physiological and mental processes

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

tolerance
state of requiring increasing quantities of the drug to gain the desired effect

wakefulness
characterized by high levels of sensory awareness, thought, and behavior