Module 1.5b - Sleep: Sleep stages and Theories

Sleep

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

Circadian Rhythm

 Our biological clock; regular bodily rhythms (Ex: Of temperature and weakness) 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. (R Sleep)

Alpha waves

The relatively slow brain waves of a relaxed, awake state.

NREM sleep

Non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep.

Hallucinations

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

Hypnagogic sensations

Bizarre experiences, such as falling jerking or a feeling of falling or floating weightlessly, while transitioning to sleep. (Also called hypnic sensations)

Delta waves

The large, slow brain waves associated with deep sleep.

Suprachiasmatic Nucleus

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.