graveyard shift

noun2

1. •
   A work shift late at night, especially one from midnight to 8 AM on a three-shift schedule.

   • I had to work the graveyard shift for most of that year, and at first I hated it, but eventually I even kind of liked it, in some ways.
2. •
   A group of workers who work during this time slot.

   • You'll have to ask the graveyard shift — the equipment was here when we left.