With respect to engineers there are a few high profile accidents where work / inspections were carried out at night where lack of sleep could easily be one of the links in the chain leading up to the event - eg the BA 1-11 windscreen (windscreen changed at night), aloha air 737 cabriolet (crown inspection c/out at night - admittedly other factors also at play here that led to the corrosion being missed)
However, night work seems to be a vital part of keeping the things in the air thanks to schedule constraints - Does this make it ok??
As a holder of a pilots license or an engineers license we are supposedly responsible to know when we are unfit for work for whatever reason but who in the current climate would feel 100% happy ringing work to say 'Sorry boss, too tired to come in tonight'?
Sometimes we can be our own worst enemy though as I don't know any of my colleagues who would turn down some overtime if the price is right! (Maybe this says we aren't paid enough but I'm sure some of you will argue this....)