Generally I smoke more during the day, only on weekends do I smoke at night, because I am partying till late.
I read a lot at night, I go through about 5 books a week on average, but generally that is unrelated to sleeping for me.
Hmmm.
Interesting point about routine, but I doubt that is it.
Still, could be I don't feel my day complete until I have gotten stoned, *grin.*