consciousness
an awareness of ourselves and our environments
circadian rhythm
the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle
suprachiasmatic nucleus (SCN)
a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, it causes the pineal gland to adjust melatonin production, modifying feelings of sleepiness.
REM sleep
rapid eye movement sleep, a recurring sleep stage during which vivid dreams commonly occur; also known as paradoxical sleep because muscles are relaxed but body is active
alpha waves
the relatively slow brain waves of a relaxed, awake state
sleep
Periodic, natural, reversible 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
NREM-1
the transition into sleep, marked by slowed breathing and irregular brain waves; hypnagogic sensations/hallucinations, and myclonic jerks may occur
NREM-2
Sleep stage characterized by its periodic sleep spindles, or bursts of rapid, rhythmic brain-wave activity. About half the night is spent in this phase.
NREM-3
sleep stage that lasts about 30 minutes and your brain emits large, slow delta waves, and you are hard to awaken.
delta waves
the large, slow brain waves associated with deep sleep
sleep spindles
bursts of rapid, rhythmic brain wave activity characteristic of stage 2 sleep
paradoxical sleep
another term for REM sleep; refers to the constrast between high amounts of brain activity and low amounts of bodily (muscle) activity
insomnia
sleep disorder characterized by recurring problems in falling or staying asleep
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 high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep, within two or three hours of falling asleep, and are seldom remembered
somnambulism
the condition of walking or performing some other activity without awakening; also known as sleepwalking - occurs during NREM-3
REM Sleep Disorder
a neurological disorder in which the person does not become paralyzed during REM sleep and thus acts out dreams
dreams
occur most often during REM sleep; may be caused by activation-synthesis, or may be a way of cementing memories
manifest content
according to Freud, the remembered story line of a dream
latent content
according to Freud, the underlying meaning of a dream (as distinct from its manifest content). Freud believed that a dream's latent content functions as a safety valve.
information processing model (of dreams)
belief by some researchers that the function of dreams is to help us sift, sort, and fix the day's experiences in our memory
activation-synthesis theory
the idea that dreams are the brain's attempt to make sense of random neural activity
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
dissociation
a split in consciousness, which allows some thoughts and behaviors to occur simultaneously with others; some believe hyponsis is a state of dissociation (divided consciousness)
psychoactive drugs
a chemical substance that alters perceptions and mood
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
depressants
drugs (such as alcohol, barbiturates, and opiates) that reduce neural activity and slow body functions.
stimulants
drugs (such as caffeine, nicotine, and the more powerful amphetamines, cocaine, and Ecstasy) that excite neural activity and speed up body functions.
hallucinogens
psychedelic ("mind-manifesting") drugs, such as LSD, that distort perceptions and evoke sensory images in the absence of sensory input
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.
ecstasy (MDMA)
a synthetic stimulant and mild hallucinogen; produces euphoria and social intimacy, but with short-term health risks and longer term harm to serotonin-producing neurons and to mood and cognition
LSD
a powerful hallucinogenic drug; also known as acid
THC
The major active ingredient in marijuana; triggers a variety of effects, including mild hallucinations.
addiction
Compulsive drug craving and use, despite adverse consequences. May also occur for certain behaviors (e.g., gambling)
substance use disorder
continued substance craving and use despite significant life disruption and/or physical risk
alcohol use disorder
Alcohol use marked by tolerance, withdrawal, and a drive to continue problematic use; popularly known as alcoholism
nicotine
A stimulating and highly addictive psychoactive drug in tobacco
cocaine
a powerfully and addictive stimulant, derived from the coca plant, producing temporarily increased alertness and euphoria
methamphetamine
A powerfully addictive drug that stimulates the central nervous system, with speeded-up body functions and associated energy and mood changes; over time, appears to reduce baseline dopamine levels