The Collaborative International Dictionary of English v.0.48:
day-and-night \day-and-night\ adj. same as around-the-clock. Syn: around-the-clock, nonstop, round-the-clock. [WordNet 1.5]WordNet (r) 3.0 (2006):
day-and-night adj 1: at all times; "around-the-clock nursing care" [syn: around-the-clock, day-and-night, nonstop, round- the-clock]