Sleep

Sleep

Biological rhythms Periodic physiological fluctuations   Circadian rhythm The biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle   Consciousness

Our awareness of ourselves and our environment

Delta waves

The large, slow brain waves associated with deep sleep

Dream

A sequence of images, emotions, and thoughts passing through a sleeping person’s mind.  Dreams are notable for their hallucinatory imagery, discontinuities, and incongruities, and for the dreamer’s delusional acceptance of the content and later difficulties remembering it.

Fantasy-prone personality

Someone who imagines and recalls experiences with lifelike vividness and who spends considerable time fantasizing

Hallucinations

False sensory experiences, such as seeing something in the absence of an external visual stimulus

Insomnia

Recurring problems in falling or staying asleep

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.   Manifest content

According to Freud, the remembered story line of a dream (as distinct from its latent content)

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks.  The sufferer may lapse directly in REM sleep, often at inopportune times

Night terrors

A sleep disorder characterized by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during Stage 4 sleep, within 2 or 3 hours of falling asleep, and are seldom remembered.

REM rebound The tendency for REM sleep to increase following REM sleep deprivation (created by repeated awakenings during REM sleep)   Sleep apnea

A sleep disorder characterized by temporary cessations of breathing during sleep and consequent momentary reawakenings