States of Consciousness

consciousness

our awareness of ourselves and our environment.

circadian rhythm

the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.

REM (rapid eye movement) sleep

rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

sleep

periodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation. (Adapted from Dement, 1999.)

hallucinations

false sensory experiences, such as seeing something in the absence of an external visual stimulus.

insomnia

recurring problems in falling or staying asleep.

narcolepsy

a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.

sleep apnea

a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

night terrors

a sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, these occur during Stage 4 sleep, within two or three hours of falling asleep, and are seldom remembered.

dream

a sequence of images, emotions, and thoughts passing through a sleeping person's mind. These are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the person 's delusional acceptance of the content and later difficulties remembering it.

REM rebound

the tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep).

hypnosis

a social interaction in which one person suggests to another that certain perceptions, feelings, thoughts, or behaviors will spontaneously occur.

dissociation

a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others.

psychoactive drug

a chemical substance that alters perceptions and moods.

tolerance

the diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug's effect.

withdrawal

the discomfort and distress that follow discontinuing the use of an addictive drug.

physical dependence

a physiological need for a drug, marked by unpleasant withdrawal symptoms when the drug is discontinued.

psychological dependence

a psychological need to use a drug, such as to relieve negative emotions.

addiction

compulsive drug craving and use, despite adverse consequences.

depressants

drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions.

barbiturates

drugs that depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment.

opiates

opium and its derivatives, such as morphine and heroin; they depress neural activity, temporarily lessening pain and anxiety.

stimulants

drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, and Ecstasy) that excite neural activity and speed up body functions.

amphetamines

drugs that stimulate neural activity, causing sped-up body functions and associated energy and mood changes.

methamphetamines

a powerfully addictive drug that stimulates the central nervous system, with sped-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels.

Ecstacy (MDMA)

a synthetic stimulant and mild hallucinogen. Produces euphoria and social intimacy, but with short-term health risks and longer-term harm to serotonin-producing neurons and to mood and cognition.

hallucinogens

psychedelic ("mind-manifesting") drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input.

LSD

a powerful hallucinogenic drug; also known as acid (lysergic acid diethylamide).

THC

the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations.

Sigmund Freud

His book, "The Interpretation of Dreams" discussed his theory that dreams were a form of wish fulfillment, attempts by the unconscious to resolve a conflict. It also discussed his ideas that would become his Oedipus complex theory.

Manifest content

according to Freud, the story of the dream.

Latent content

according to Freud, the underlying meaning of a dream (as distinct from its manifest content).