This is a very tricky one....but the fact is that people start to leave nighters from 3am on. And after 5am the poor DJ's have a half empty room to play to....also, staff want to get home....I think 6am is sensible now....also, if the room is booked for the next day, the managment need to get some sleep, so they can clean the room, and set up all over again... ....in the old days when there was no alchohol and the venue was just booked for the one night, there was no problem. And of course we were all young, and had nothing to rush home for....
Phil.