Another alternative, if it's too difficult to change your sleeping schedule, is to go ahead and go to the bars/clubs etc. and befriend the staff. They usually appreciate their late night regulars who aren't drunk and obnoxious at closing time. Many of the folks in the "late-night" service industry tend to hang out for some few hours after work, thought it is usually at invite-only after-hours type establishments or in rotating "house-party lite" type situations. Most of them like to party, but tend to stick into a tighter social circle. These mini-circles tend to contain many attractive women (hostesses, food servers, ****tail waitresses, and hot bartenders, who all tend to be hired, at least in part, due to their looks). The "gatekeepers" to this sort of scene usually are the more popular male bartenders, become solid friends with these guys...and you're in.