I don't work nights but I just can't condone this. I bust my ass all day "working to rule" and am proud to do a good job with the skills I have. I know it's tough to stay up all night (I did it years ago for a previous job) but at the end of the day - you are at work and should act like it. It may be that this was winked at by certain supervisors and it seems callous to crack down out of the blue, but it's a good reminder to all of us that we should follow the book every time.