Why is the phrase "graveyard shift" used for late-night work?
Current popular explanations for the origin of the phrase "graveyard shift" reference the 19th century problem of accidentally burying people who were still alive. To prevent this from happening, the story goes, caskets were equipped with a bell-ringing device enabling a waking "corpse" to notify the world that they were no longer dead. The graveyard attendants who remained vigilant throughout the day and night worked the graveyard shift.
According to Michael Quinion at World Wide Words the above explanation is merely a story and nothing more. He explains that the "graveyard shift is an evocative term for the night shift between about midnight and eight in the morning, when - no matter how often you've worked it - your skin is clammy, there's sand behind your eyeballs, and the world is creepily silent, like the graveyard. The phrase dates only from the early years of the twentieth century."