Circandian Rhythm

A cycle or rhythm this is roughly 24 hours long; the cyclical daily fluctuations in biological and psychological process

Superchiasmatic nucle us (SCN)

A cluster of neurons in the hypothalamus in the brain that governs the timing of circadian rhythms

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness

Electroencephalograph

An instrument that uses electrodes placed on the scale to measure and record the brain’s electrical activity

EEG (electroencephalogram)

The graphic record of brain activity produced by an electroencephalograph

REM sleep

Type of sleep during which rapid eye movements and dreaming usually occur and voluntary muscle activity is suppressed: also called active sleep or paradoxical sleep

NREM Sleep

Quiet typically dreamless sleep in which rapid eye movements are absent; divided into four stages; also called quiet sleep

Beta brain waves

Brain-wave pattern associated with alert wakefulness

Alpha brain waves

Brain-wave pattern associated with relaxed wakefulness and drowsiness

Hypnagogic hallucinations

Vivid sensory phenomena that occur during the onset of sleep

Sleep spindles

Short bursts of brain activity that characterize stage 2 NREM sleep

K complex

Single but large high-voltage spike of brain activity that characterizes stage 2 NREM sleep

REM rebound

A phenomenon in which a person who is deprived of REM sleep greatly increases the amount of time spent in REM sleep at the first opportunity to sleep uninterrupted

Restorative theory of sleep

The view that sleep and dreaming are essential to normal physical and mental functioning

Adaptive theory of sleep

The view that the unique sleep patterns of different animals evolved over time to help promote survival and environmental adaptation; also referred to as the evolutionary theory of sleep

Sleep disorders

Serious disturbances in the normal sleep pattern that interfere with daytime functioning and cause subjective distress

Insomnia

A condition in which a person regularly experiences an inability to fall asleep, to stay asleep, or to feel adequately rested by sleep

Restless legs syndrome (RLS)

A condition in which unpleasant sensations in the lower legs are accompanied by an irresistible urge to move the legs, temporarily relieving the unpleasant sensation but disrupting sleep

Sleep apnea

A sleep disorder in which the person repeatedly stops breathing during sleep

Sleepwalking

A sleep disturbance characterized by an episode of walking or performing other actions during stage 3 or stage 4 NREM sleep; also called somnambulism

Night terrors

A sleep disturbance characterized by an episode of increased physiological arousal, intense fear and panic, frightening hallucinations, and no recall of the episode the next morning; typically occurs during stage 3 or stage 4 NREM sleep; also called sleep terrors

Parasomnias

A category of sleep disorders characterized by arousal or activation during sleep or sleep transitions; includes sleepwalking, night terrors, sleep bruxism, and REM sleep behavior disorder

REM sleep behavior disorder

A sleep disorder in which the sleeper acts out his or her dreams

Dream

A storylike episode of unfolding mental imagery during sleep

Nightmare

A frightening or unpleasant anxiety dream that occurs during REM sleep

Manifest content

In Freud’s psychoanalytic theory, the elements of a dream that are consciously experienced and remembered by the dreamer

Latent content

In Freud’s psychoanalytic theory, the unconscious wishes, thoughts, and urges that are concealed in the manifest content of a dream

Activation-synthesis model of dreaming

The theory that brain activity during sleep images (activation), which are combined by the brain into a dream story (synthesis)

Hypnosis

A cooperative social interaction in which the hypnotized person responds to the hypnotist’s suggestions which changes in perception, memory, and behavior

Posthypnotic suggestion

A suggestion made during hypnosis that the person should carry out a specific instruction following the hypnotic session

Posthypnotic amnesia

The inability to recall specific information because of a hypnotic suggestion

Hypermnesia

The supposed enhancement of a person’s memory for past events through a hypnotic suggestion

Dissociations

The splitting of consciousness into two or more simultaneous streams of mental activity

Neodissoication theory of hypnosis

Theory proposed by Ernest Hilgard that explains hypnotic effects as being due to the splitting of consciousness into two simultaneous streams of mental activity, only one of which the hypnotic participant is consciously aware of during hypnosis

Hidden observer

Hilgard’s term for the hidden, or dissociated stream of mental activity during hypnosis

Meditation

Any one of a number of sustained concentration techniques that focus attention and heighten awareness

Psychoactive drug

A drug that alters consciousness, perception, mood, and behavior

Physical dependence

A condition in which a person has physically adapted to a drug so that he or she must take the drug regularly in order avoid withdrawal symptoms

Drug tolerance

A condition in which increasing amounts of a physically addictive drug are needed to produce the original, desired effect

Withdrawal symptoms

Unpleasant physical reactions, combined with intense drug cravings, that occur when a person abstains from a drug on which he or she is physically dependant

Drug rebound effect

Withdrawal symptoms that are the opposite of a physically addictive drug’s action

Drug abuse

Recurrent drug use that results in disruptions in academic, social, or occupational functioning or in legal or psychological problems

Depressants

A category of psychoactive drugs that depress or inhibit brain activity

Barbiturates

A category of depressant drugs that reduce anxiety and produce sleepiness

Tranquilizers

Depressant drugs that relieve anxiety

Inhalants

Chemical substances that are inhaled to produce an alteration in consciousness

Opiates

A category of psychoactive drugs that are chemically similar to morphine and have strong pain-relieving properties

Stimulants

A category of psychoactive drugs that increase brain activity, arouse behavior, and increase mental alertness

Caffeine

A stimulant drug found in coffee, tea, cola drinks, chocolate, and many over-the- counter medications

Nicotine

A stimulant drug found in tobacco products

Amphetamines

A class of stimulant drugs that arouse the central nervous system and suppress appetite

Cocaine

A stimulant drug derived from the coca tree

Stimulant-induced psychosis

Schizophrenia-like symptoms that can occur as the result of prolonged amphetamine or cocaine use; also called amphetamine psychosis or cocaine psychosis

Psychedelic drugs

A category of psychoactive drugs that create sensory and perceptual distortions, alter mood, and affect judgment

Mescaline

A psychedelic drug derived from the peyote cactus

LSD

A synthetic drug

Marijuana

A psychoactive drug derived from the hemp plant

MDMA or ecstasy

Synthetic club drug that combines stimulant and mild psychedelic effects

Dissociative anesthetics

Class of drugs that reduce sensitivity to pain and produce feelings of detachment and dissociation; includes the club drugs phencyclidine (PCP) and ketamine

Sigmund Freud ( )

Founder of psychoanalysis; proposed that dream images are disguised and symbolic expressions of unconscious wishes and urges

Ernest R. Hilgard ( )

American psychologist who extensively studied hynosis and advanced the neodissociation theory of hypnosis

J. Allan Hobson (b. 1933)

Contemporary American psychiatrist and neurobiologist who has extensively researched sleep and dreaming; proposed the activation-synthesis model of dreaming

William James ( )

American psychologist and philosopher who proposed that the subjective experience of consciousness is an ongoing stream of mental activity