From Longman Dictionary of Contemporary Englishnight and daynight and day (also day and night)CONTINUOUS all the time SYN continuously Being together night and day can put a great pressure on any relationship. → day
Examples from the Corpus
night and day• My next door neighbor's dog barks day and night.• I had to be at his beck and call, night and day.• She drove me crazy, night and day, she wanted sneakers, she wanted sneakers.• The only way into his protective case was through a little trap door he kept locked night and day.• He is sleepless, crying out night and day.• Does that thing play night and day, Harding?• Leave pumped water to run night and day to increase oxygen content; add more water if needed.• Even those who live in the City must wear spectacles night and day.• Seizing upon this opportunity, the Santanistas worked night and day to undermine the Herrera administration. 