The only airport sleepovers I can think of are both planned. One in ORD so I could bring a friend back in the morning (NW required you to fly with a friend in most circumstances) and another in SEA so I could catch an early flight to HNL the next day.

Looking back, that ORD one was kind of suicidal. I had to work back in MSP at 11 something that morning, and also had to give my friend a ride home. I ended up flying in to MSP with her, didn't get on the first flight, got on the second, took the shuttle to the parking lot while she waited for her bag, picked her up from the airport, dropped her off at her house, went back to my (parents') place, got a fast shower and change, then got to work. They said we had to swipe 7 minutes before our shift started, I believe it was (looking back, I don't think that was legal!) or else we could get an "on-time tardy" as it was called. I think I clocked in right as my shift started. Told my supervisor sorry, but I was in Chicago earlier today so I had one of those on-time tardies. "You flew in from Chicago today?" (with a look of disbelief) "Yup" "...Don't worry about it."