Having worked nights
Early in my career (not as a pilot!) I can tell you that sometimes coming off "rest" ie a couple days of normal hours can be the worst, cos of course you stay up in daylight hrs to be w friends and family....your inner clock adjusts a bit....then you go back on a midnight shift and your biorhythms hit rock bottom when you're supposed to be awake and alert.
Awful. Can't imagine being in charge of an aircraft feeling like that.
They'd give us a month on day shift....it was 2 weeks before you felt normal...then you'd have 2 weeks feeling good, then back on mid nights and have to flip round again.
Not healthy.