Its called "Set and Setting" - http://en.wikipedia.org/wiki/Set_and_setting

I prefer being high in the day, mostly cause when I toke at night, then you tend to waste it by falling asleep. This is only in certain situations though, like when I have some people over spending the night and we watch a movie, but everyone just nods off after a half hour. But if I'm out and about at night high then its all good. I just like to keep busy when high.