It's not even just the work aspect, per-say, I know for myself late at night is when I feel more... Creative I guess the word would be. Add in a little exhaustion and it's silly creative time.
yeah, often the script writing brain storming season doesn't really start until you've been spinning your wheels for 8 hours going nowhere and now it's 2am and someone just said "but what if she never went outside"
sometimes we don't get there until we get a little goofy. I've heard it might just be how creatives work.
And if that wasn't required and the hours were paid, it'd be no problem. Especially if they allowed people to flex their work times so working late nights was feasible.