Earplugs wont be a bad idea. At least if they sleep off so well they can tell thier colleagues to wake them up. I am assuming the bunk beds are comfortable as well. On a recent vigin atlantic flight i was shocked to discover the crew rest area was under the main cabin near where i was seating.
There was a door that led to a stairway and could see the beds. Considering the fact that persengers will be moving around during the flight wont this be noisier than having it at the rear like the 747.