The crew rest issue is as old as the hills.
It is true operational crews may live in hot, sandy, noisy environments and will suffer interupted sleep etc. Curiously the body eventually gets used to the disturbance as a pattern and rest of some sort becomes possible.
Crews en route, continually changing environments, do not have the chance to acclaimatise to appallng conditions. One long running issue, especially for day slips, was the daily regularity of cleaners and their vaccum cleaners or the inflexibility of meals times with breakfast at 7pm consisting of Roast Beef when the body is crying out for a bacon sarni.
I am fortunate never having had to operate a crew slip system, but I can sympathise. It may not be everyone's idea of hell, but it still takes its toll.