catch some Z's vs sleep

catch some Z's is not a noun while sleep is a noun.

Word	Noun	Adjective	Verb	Adverb
catch some Z's	No	No	Yes	No
sleep	Yes	No	Yes	No

As verbs, catch some Z's and sleep are synonyms defined as:

Other synonyms of catch some Z's include kip, log Z's, slumber.

catch some Z's (noun)	sleep (noun)
	a natural and periodic state of rest during which consciousness of the world is suspended
	euphemisms for death (based on an analogy between lying in a bed and in a tomb)
	a torpid state resembling deep sleep
	a period of time spent sleeping

catch some Z's (verb)	sleep (verb)
be asleep	be asleep
	be able to accommodate for sleeping