Alchohol
A variety of beverages containing ethyl alcohol.
Ascending reticular activating system (ARAS)
The afferent fibers running through the reticular formation that influence physiological arousal.
Biological rhythms
Periodic fluctuations in physiological functioning.
Cannabis
The hemp plant from which marijuana, hashish, and THC are derived.
Circadian rhythms
The 24-hour biological cycles found in humans and many other species.
Dissociation
A splitting off of mental processes into two separate, simultaneous streams of awareness.
Electroencephalograph (EEG)
A device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp.
Electromyograph (EMG)
A device that records muscular activity and tension.
Electrooculograph (EOG)
A device that records eye movements.
Hallucinogens
A diverse group of drugs that have powerful effects on mental and emotional functioning, marked most prominently by distortions in sensory and perceptual experience.
Hypnosis
A systematic procedure that typically produces a heightened state of suggestibility.
Insomnia
Chronic problems in getting adequate sleep.
Latent content
According to Freud, the hidden or disguised meaning of the events in a dream.
Lucid dreams
Dreams in which people can think clearly about the circumstances of waking life and the fact that they are dreaming, yet they remain asleep in the midst of a vivid dream.
Manifest content
According to Freud, the plot of a dream at a surface level.
MDMA
A compound drug related to both amphetamines and hallucinogens, especially mescaline; commonly called "ecstasy.
Meditation
A family of mental exercises in which a conscious attempt is made to focus attention in a nonanalytical way.
Narcolepsy
A disease marked by sudden and irresistible onsets of sleep during normal waking periods.
Narcotics (opiates)
Drugs derived from opium that are capable of relieving pain.
Night terrors
Abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic.
Nightmares
Anxiety-arousing dreams that lead to awakening, usually from REM sleep.
Non-REM (NREM) sleep
Sleep stages 1 through 4, which are marked by an absence of rapid eye movements, relatively little dreaming, and varied EEG activity.
Physical dependence
The condition that exists when a person must continue to take a drug to avoid withdrawal illness.
Psychoactive drugs
Chemical substances that modify mental, emotional, or behavioral functioning.
Psychological dependence
The condition that exists when a person must continue to take a drug in order to satisfy intense mental and emotional craving for the drug.
REM sleep
A deep stage of sleep marked by rapid eye movements, high-frequency brain waves, and dreaming.
Sedatives
Sleep-inducing drugs that tend to decrease central nervous system activation and behavioral activity.
Sleep apnea
A sleep disorder characterized by frequent reflexive gasping for air that awakens a person and disrupts sleep.
Slow-wave sleep (SWS)
Sleep stages 3 and 4, during which low-frequency delta waves become prominent in EEG recordings.
Somnambulism (sleepwalking)
Arising and wandering about while remaining asleep.
Stimulants
Drugs that tend to increase central nervous system activation and behavioral activity.
Tolerance
A progressive decrease in a person's responsiveness to a drug.