I would think it would be impossible to nod off while approaching a 7000' runway at night in a widebody, no ILS, hilly terrain, etc....
I agree. Although we've yet to hear of their duty day, at most their reaction time might have been affected.
Flying all-nighters into MEX (arrive 0000L, sit for 4 hours - depart 0400L four nights in a row) by the end of the month I felt like I had toothpicks holding my eyes open. But to actually fall asleep on the approach? - Hardly.