This is a great topic for a thread! I think most of these suggestions are spot on for me. I have lots of online business to attend to (as Chrissi suggests) so I often find myself up until around 1 am on worknights (which, is a habit I really want to break since I think it's really wearing on me now to have such little sleep routinely). By online "business" I mean... Facebook stuff, BetterMost stuff, email and fanfic... all of these things end up taking hours almost every night and to get through all the stuff I want to check in on, sleep gets sacrificed.
I also agree with the idea of somehow making tomorrow not come so quickly by staying up late. It's an interesting psychological phenomenon, but it sounds right to me too in terms of my experience.
And, I also think hanging out online too long most nights is a way to mask insomnia. In grad school I had really bad insomnia. I used to start in on dissertation work after Conan O'Brien finished many evenings... so I would often be up almost all night working... and then I'd sleep a lot of the day. I have a much better time staying asleep than falling asleep. My ideal sleeping hours are morning hours usually... so getting up early for a normal work day is very hard for me. Essentially I think I'm very naturally a night owl when left to my own devices and my own self-determined schedule (which I had in grad school... a self determined schedule).