Graveyard shift, night shift or third shift (3rd shift) means a shift of work running through the early hours of the morning, especially shifts from midnight until 08:00 or from 23:00 until 07:00. There is no certainty as to the origin of this phrase; it is little more than "an evocative term for the night shift … when … your skin is clammy, there's sand behind your eyeballs, and the world is creepily silent, like the graveyard."
**It was a dark and stormy night. Actually it wasn't exactly stormy, just dark. But it was night. A motion sensor went off in one of the Multi-Purpose rooms. Hmm, what could it be? Nothing on the cameras, but the alarm kept tripping. My co-worker left the room, and I was alone with the monitors. I saw it! I saw the cat burglar as clear as day, walking across the MP room. Actually it wasn't exactly a burglar, but it was a cat. As in meow, here Kitty Kitty. A cat, stuck in the MP room. So glad I didn't call the sheriff.**