Latest I've ever been up is probably around 9:00 PM the next day, but that's really freaking hard and usually when I pull this stuff I have trouble making it past 2:00 PM the next day. I think my record for straight hours awake is 38, without coffee. But I'm getting old so now I try to go to bed by at least 5:00 AM.
That's only on weekends though, weekdays I'm really strict about going to bed by midnight at the latest. I'll go to bed at 9:00 PM if I can help it.