A night person is the opposite of a morning person. They feel better in the afternoon than the early morning, and seem to feel extremely productive in the evening hours instead of during the day like everyone else.
Usually these people don't want to go to bed until sometime after midnight (apparently with typical "delayed sleep phase" the average hour is 2 AM) and I've found that sometime between midnight and 3 AM is best for me. When I go to bed between 9 and midnight it's either because I'm sick or because I'm forced to for a job or something.
But if I get in a habit of staying up after 4 AM, that's bad. It feels off-kilter. I don't think I'd like being a third shift person, though like I said I've worked second shift for many years and prefer it. In college my classes were usually never before 11 AM, and after 1 PM if possible.
I did take an 8 o'clock class in summer school for six weeks and it just about killed me.
This pattern started in high school, I noticed. Actully even as early as 6th or 7th grade I would stay up and watch Saturday Night Live until 1 or 2 AM on weekends. But by the time I was a junior and senior in high school it became a problem, like that I would want to stay up until like 1 AM and have to get up at 6 AM and often I'd over sleep, and if I got up on time I'd end up taking a long nap after school - I mean for like two hours - so I'd not want to go to bed, wash, rinse, repeat.
And it wasn't for lack of trying on my grandparents' part. They tried their damnedest to instill a bed time into me. But even as a CHILD I remember tip toeing and getting up and eavesdropping on their conversations, or singing to myself or talking to myself or listening to the radio and being told to go to sleep.
In high school they tried all kinds of shenanigans to get me into bed on time, including hiding the house telephone from me (there were no cell phones then) but it was a cordless so I'd just sneak and grab the phone after they dozed off by 10 PM (they were both nice, well-disciplined SJ morning people).