Sleep and Dreams Vocabulary

Circadian Rhythm

Our internal biological; 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. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.

Alpha Waves

Relatively slow brain waves of a relaxed, awake state.

Sleep

A periodic, natural loss of consciousness--as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation.

Delta Waves

Large, slow brain waves associated with deep sleep.

Suprachiasmatic Nucleus (SCN)

A pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN adjusts melatonin production, thus modifying our feelings of sleepiness.

Insomnia

Recurring problems in falling or staying asleep.

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks, sometimes lapsing directly into REM sleep.

Sleep Apnea

A sleep disorder in which a sleeping repeatedly stops breathing until blood oxygen is so low the person awakens just long enough to draw a breath.

Dream

A sequence of images, emotions, and thoughts passing through a sleeping persons mind.

Manifest Content

According to Freud, the remembered storyline in a dream.

Latent Content

According to Freud, the underlying meaning of a dream.

REM Rebound

The tendency for REM sleep to increase following REM sleep deprivation.