Its this chopping and changing week to week and in Jetstars case it seems, within the week, that causes the most of fatigue through unstable sleep cycles.
Spot on. My roster is not as demanding as J* but I really struggle to get enough rest if I have a 29hour break between a midnight landing and a 5 am sign on.
On the face of it a 29 hour break is a big break, but for me, If I finish at midnight, home by 0045hrs, I won't wind down enough to sleep until about 2am, so then if I get 8 hours I'm awake at 10am and have to be in bed again asleep at 8pm in order to get a full nights sleep. The reality is I will still be awake at 11pm or if I'm unlucky midnight, I'l get about 3hours forty five minutes sleep, and then my alarm goes off for a rostered 11 hour day.
So for me it's the re-setting of the body clock that is difficult and my roster is as I said, less demanding than the chop/change J* rosters I have seen.