Non-REM (nonrapid eye movement) sleep, which is the normal period of dreamless, lighter sleep as compared to the deeper REM sleep. NREM sleep accounts for the major portion of sleep.

a recurring sleep state during which rapid eye movements do not occur and dreaming does not occur; accounts for about 75% of normal sleep time

Non-rapid eye movement sleep. A stage of sleep in which brain activity and bodily functions slow down. NREM sleep accounts for the largest portion of the sleep cycle.

(Non-REM sleep) a deep restful sleep rate; also called slow wave sleep

the stages of sleep not associated with rapid eye movements and marked by relatively little dreaming. (201)

All sleep stages other than REM sleep; made up of sleep stages 1 through 4. Characterized by a slowing of brain waves and some physiological functions. A state that lacks the visible motility of rapid eye movements and twitches. See Sleep Stages.