consciousness
our awareness of ourselves and our environment
circadian rhythm
the biological clock; regular bodily rhythms that occur on a 24-hour cycle
REM sleep
rapid eye moment 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
alpha waves
the relatively slow brain waves of a relaxed, awake state
sleep
periodic, natural loss of consciousness - as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation
hallucinations
false sensory experiences, such as seeing something in the absence of an external visual stimulus
delta waves
the large, slow brain waves associated with deep sleep
NREM sleep
non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep
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 a high arousal and an appearance of being terrified; unlike nightmares, night terrors 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. Dreams are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the dreamer's delusional acceptance of the content and later difficultie
manifest content
according to Freud, the remembered story line of a dream (as distinct from its latent, or hidden, content)
latent content
according to Freud, the underlying meaning of a dream (as distinct from its manifest content)
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
posthypnotic suggestions
a suggestion, made during a hypnosis session, to be carried out after the subject is no longer hypnotized; used by some clinicians to help control undesired symptoms and behaviors
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 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 more powerful amphetamines, cocaine, and ecstasy) that excite neural activity and speed up the body functions
amphetamines
drugs that stimulate neural activity, causing sped-up body functions and associated energy and mood changes
methamphetamine
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
near-death experience
an altered state of consciousness reported after a close brush with death (such as cardiac arrest); often similar to drug-induced hallucinations
THC
the major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations