| A | B |
|---|
| consciousness | awareness of the environment and of one's own existence, sensations and thoughts |
| states of consciousness | distinctive and sicrete patterns in the functioning of consciousness, characterized by particular modes of perception, thought, memory or feeling |
| biological rhythm | a periodic, more or less regular fluctuation in a biological system; may or may not have psychological implications |
| entrainment | the synchronization of biological rhythms with external cues, such as fluctuations in daylight |
| circadian rhythm | a biological rhythm with a period of about 24 hours |
| infradian rhythm | a biological rhythm that occurs less frequently than once a day |
| ultradian rhythm | a biological rhythm that occurs more frequently than once a day |
| rapid eye movement (REM) sleep | sleep periods characterized by eye movement, loss of muscle tone and dreaming |
| alpha waves | relatively large, slow brain waves characteristic of relaxed wakefulness |
| delta waves | slow, regular brin waves characteristic of Stage 3 and Stage 4 sleep |
| lucid dream | a dream in which the dreamer is aware of dreaming |
| activation-synthesis theory | the theory that dreaming results from the cortical synthesis and interpretation of neural signals triggered by activity in the lower part of the brain |
| altered state of consciousness | a state of consciousness that differs from ordinary wakefulness or sleep |
| psychoactive drug | a drug capable of influencing perception, mood, cognition and behavior |
| stimulants | drugs that speed up activity in the central nervous system |
| depressants | drugs that slow down activity in the central nervous system |
| opiates | drugs, derived from the opium poppy, that relieve pain and commonly produce euphoria |
| psychedelic drugs | consciousness-altering drugs that produce hallucinations, change thought processes, or disrupt the normal perception of time and space |
| tolerance | increased resistance to a drug's effects accompanying continued use; as tolerance develops, larger doses are required to prodice effects once brought about by smaller ones |
| withdrawal symptoms | physical and psychological symptoms that occur when someone addicted to a drug stops taking it |
| hypnosis | a procedure in which the practitioner suggests changes in the sensations, perceptions, thoughts, feelings or behavior of the subject |
