I'm guilty of staying up later than I should and therefore getting less sleep than I'd like to. I don't think it's about an addiction to the effects of being sleep deprived though. I have always functioned well on less sleep than most people require, it takes a severe lack of sleep before I'm feeling groggy and like my functioning is impaired, although I have noticed in the last few years as I'm getting older, that the threshold for what I consider a severe lack of sleep has moved, and I am affected more easily than I used to be.

The thing that keeps me up beyond my bed time is just the feeling that comes with being up late - my house is in order, my children are asleep, the chores are done, nobody is going to phone or knock on my door, I don't feel any pressure to be doing anything "more productive"...it's just pure, relaxing "me time".