Obviously no problem with circadian rhythm because no jet lag.
Obviously?? Not really, I regularly finish at midnight, get home at 0030, fall asleep about 0200, sleep til 1000, then have to start at 0530 the next day. This means that to get 8 hrs sleep I have to be in bed asleep by 2030hrs. It has never happened once because I simply cannot sleep after being awake for such a short period of time. I have a big break, 29 hours, but the cycle is repeated over and over with quite long four sector days and I am at the point where I might try sleeping pills even though I am fairly young, fit, and in good health. It's all completely legal and completely fatiguing......If I did the same flying hours with 10 hour breaks it would not fatigue me, I know because I've done it before. Can't see what jet-lag has to do with it at all actually.