sleep vs time period

sleep and time period both are nouns.

Word	Noun	Adjective	Verb	Adverb
sleep	Yes	No	Yes	No
time period	Yes	No	No	No

As nouns, time period is a hypernym of sleep; that is, time period is a word with a broader meaning than sleep:

Other hypernyms of sleep include period, period of time.

sleep (noun)	time period (noun)
a natural and periodic state of rest during which consciousness of the world is suspended	an amount of time
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

sleep (verb)	time period (verb)
be asleep
be able to accommodate for sleeping