noun, adverb, noun which may take the genitive case particle 'no'
day and night; around the clock
Used as a noun, adverb, or no-adjective to express continuous activity or state throughout day and night.
The construction continued day and night.
The temperature difference between day and night is large.
He worked day and night to pay off his debt.
That convenience store is open around the clock.
reversal of day and night; day-night reversal