Vocabulary 1.5 Sleep and Consciousness

Sleep/wake cycle

the pattern of alternating sleep and wakefulness that typically recurs every 24 hours as part of the body's internal biological clock.

Circadian rhythm

the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.

Jet lag

a disruption of circadian rhythm that occurs when travel across time zones causes the internal biological clock to be out of sync with the external day-night cycle.

Shift work

a disruption of circadian rhythm resulting from work schedules that require being awake when the body's biological clock expects sleep.

EEG - stages of sleep

the stages of sleep are defined and measured by characteristic patterns of brain-wave activity recorded with an electroencephalogram (EEG).

NREM (stages 1-3)

non-rapid eye movement sleep; the stages of sleep that are not REM and during which slower brain waves and minimal dreaming occur.

Hypnagogic sensations

brief sensory experiences (such as a feeling of falling or floating weightlessly) that sometimes occur while transitioning into sleep, near the beginning of NREM-1 sleep.

REM

rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur.

Paradoxical sleep

another term for REM sleep, because the muscles are relaxed (except for minor twitches) while other body systems are active.

Dreaming

a sequence of images, emotions, and thoughts passing through a sleeping person's mind; most vivid and frequent during REM sleep.

REM rebound

the tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep).

Activation-synthesis theory

the theory that dreams result from the brain's attempt to make sense of random neural activity.

Consolidation theory

the view that dreaming and REM sleep contribute to memory formation by strengthening and stabilizing recently learned information.

Insomnia

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.

REM sleep behavior disorder

a sleep disorder in which a person physically acts out dreams because of a failure of the usual muscle paralysis during REM sleep.

Sleep apnea

a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.

Somnambulism (sleepwalking)

a disorder of arousal that occurs during NREM-3 sleep and involves walking or performing other activities while asleep.