States of Consiousness

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 (consolidation) 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)

beta waves

smaller and faster brain waves, typically indicating an active, awake mental state

pineal gland

secretes melatonin to trigger the onset of sleepiness

Melatonin

A hormone manufactured by the pineal gland that produces sleepiness.

Dual-processing

the principle that information is often simultaneously processed on separate conscious and unconscious tracks

Sequential processing

occurs when the brain computes information step-by-step in a methodical and linear matter

Parallel processing

the processing of many aspects of a problem simultaneously; the brain's natural mode of information processing for many functions, including vision. Contrasts with the step-by-step (serial) processing of most computers and of conscious problem solving.

Cognitive neuroscience

the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language)

blindsight

a condition in which a person can respond to a visual stimulus without consciously experiencing it

hypnogogic sensations

bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning to sleep