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a state of awareness, including a person's feelings, sensations, ideas, and perceptions

REM sleep

a stage of sleep characterized by rapid eye movements, a high level of brain activity, a deep relaxation of the muscles, and dreaming

circadian rhythm

the rhythm of activity and inactivity lasting approximately one day


the failure to get enough sleep at night in order to feel rested the next day

sleep apnea

a sleep disorder in which a person has trouble breathing while asleep


a condition characterized by suddenly falling asleep or feeling very sleepy during the day

night terrors

sleep disruptions that occur during State IV of sleep, involving screaming, panic, or confusion


a state of consciousness resulting from a narrowed focus of attention and characterized by heightened suggestibility

posthypnotic suggestion

a suggestion made during hypnosis that influences the participant's behavior afterward


the process of learning to control bodily states with the help of machines monitoring the states to be controlled


the focusing of attention to clear one's mind and produce relaxation


perceptions that have no direct external cause


drugs that often produce hallucinations


a potent psychedelic drug that produces distortions of perception and thought

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