graveyard shift A work shift usually from twelve midnight until eight in the morning; any late-night shift; also the graveyard watch . Factories running 24 hours a day employ three shifts—day, swing, and midnight or. graveyard. The expression gained currency during World War II when so many factories were operating around-the-clock. The phrase, American slang and dating from the early part of this century, is an allusion to the late hour of the shift, which works in the dead of night when it is quiet and still as a graveyard.