Haha hopefully it doesn't happen!
That's crazy @_@ People will go nuts for what they really want lol
Um.... I think they leave by their bedtime or by midnight of that day. They leave immediately when someone picks them up. You can still keep her around if you keep resetting the time back before the next day, I think. I'm really not wholly sure though, sorry. :/
You should probably get some sleep, too. I remember going on 2 all-nighters, and that messed me up terribly >.<