NREM vs NREM sleep

NREM and NREM sleep both are nouns.

Word	Noun	Adjective	Verb	Adverb
NREM	Yes	No	No	No
NREM sleep	Yes	No	No	No

As nouns, NREM and NREM sleep are synonyms defined as:

NREM and NREM 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

Other synonyms of NREM include nonrapid eye movement, nonrapid eye movement sleep, orthodox sleep.

NREM (noun)	NREM sleep (noun)
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	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