Consciousness
Our awareness of ourselves and our environment.
Dissociation
A split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others.
Circadian Rhythm
The biological clock; regular bodily rhythms that occur on a 24-hour cycle.
REM Sleep
Rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur.
Alpha Waves
The relatively slow brain waves of a relaxed, awake state.
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.
Suprachiasmatic Nucleus
A pair of cell clusters in the hypothalamus that controls circadian rhythm.
Insomnia
Recurring problems in falling or staying asleep.
Narcolepsy
A sleep disorder characterized by uncontrollable sleep attacks.
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.
Dream
A sequence of images, emotions, and thoughts passing through a sleeping person’s mind.
REM Rebound
The tendency for REM sleep to increase following REM sleep deprivation.
Manifest Content
According to Freud, the remembered storyline of a dream.
Latent Content
According to Freud, the underlying meaning of a dream.
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 same effect.
Addiction
Compulsive craving of drugs or certain behaviors despite known adverse consequences.
Withdrawal
The discomfort and distress that follow discontinuing an addictive drug or behavior.
Depressants
Drugs that reduce neural activity and slow body functions.
Opiates
Opium and its derivatives, such as morphine and heroin; they depress neural activity, temporarily lessening pain and anxiety.
Stimulants
Drugs that excite neural activity and speed up body functions.
Cocaine
A powerful and addictive stimulant, derived from the coca plant, producing temporarily increased alertness and euphoria.
Hallucinogens
Psychedelic 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.
THC
The major active ingredient in marijuana; triggers a variety of effects, including mild hallucinogens.