I'm going to reply to this thread; it's so lonely.
When left to my own devices, I typically go to bed around 5:00 in the morning and get up at 1:00-2:00 in the afternoon. That is my natural sleep cycle, I think. Last summer, I decided to find a job on night shift, and I did get one for June and July that was 10:00-7:00 five nights a week. I thought that that would be great for my sleeping because I am basically nocturnal as it is, and I really don't sleep when in school because rather than going to bed earlier to make up for having to get up earlier my body will not tire at all until at least 4:00 in the morning, and it's getting progressively worse as the years pass, since my freshman year of high school (which I spent going to bed at 7:30-8:00 every night for most of it because I have no idea what was wrong with me for seven months, but something was).
It didn't work out that well, though. I'd usually end up staying awake until 9:00 or 10:00 in the morning and then not be able to sleep past 2:00ish... Yeeeeaaaah. Night shift is out as a viable option in my future, but days aren't looking much better. I take diphenhydramine and Nyquil to help me fall asleep a lot at school when I know that I will be exhausted the next day if I don't.
When I was not doing so well, I'd go through cycles of sleeping 18-20 hours a day and then not sleeping at all for 2-3 days, only crashing when I induced it myself by taking a ton of diphenhydramine (looked it up online since then, and those doses should have made me stay awake and wildly hallucinate, the opposite of what I wanted; i don't know why they worked). Those were interesting times.
tl;dr: I'm a complete night owl, but I also need it to be night time for me to get good sleep.
I'm also so there with you on being productive late at night... This past semester I pulled four all-nighters getting papers written and got 98-100 on all of them. It worked well. I work so much better if I don't split things up into a little here, a little there, and just plug away and get everything done at once. It got ridiculous at the end of last semester when I had to work basically non-stop for two weeks and started eating basically just one meal a day because I forget to eat when I'm that dedicated to something (a friend with the same problem and I promised to remind each other to eat, buuut it didn't work because two absorbed people... yeah
), but I love the feeling of working and getting things done when I'm in that mode. Oh, it's just fantastic. When I write poetry and songs and prose, I always have things come like bam bam bam in the middle of the night, too. I can write something in five minutes then, easily; have me do it at noon, though, and I will struggle and take well over an hour to get a poem written. When I'm at school i get most of my work done 12:00-5:00 in the morning. I hang out with people all day long, and they NEVER see me doing homework, but after my roommate goes to bed, it's crunch time. I just don't sleep.
). When I have to get up early though, I really don't mind though. I don't like mornings, but I'm usually really personable in the morning oddly enough. It used to drive my very grumpy roommate nuts because we'd go to sleep around 5, and then 3 hours later I'd be awake and cheerful. It usually ended up with various items being thrown at me.