I suppose my late night hours are more a result of a wonky schedule than actual insomnia, though that does come into play sometimes. I've always been more of a night person than a day person. Early mornings during my school years were especially brutal, after graduation, my summertime hours just seemed to stick and continue to stick to this day.
It's the best time for me to be creative, thanks to the dark, the quiet, and the lack of distractions (though YouTube can be a killer). Whether it's writing or visual art, my best stuff happens when everyone's sleeping. In recent years, I've been doing a lot of animation for short films. I recently finished a film that took me over 1,300 hours of animating and most, if not all of the animation was done at night.
The schedule's hard to shake though. I'm in between projects, it's currently about 6 AM and here I am, still up. In my creative downtime, the dark hours have become my DVD hours, I'm currently zipping through my Futurama box sets (Oh, that Zoidberg...) and milking Netflix for all it's worth.
My nocturnal ways are working fairly well for me so far, I get my work done and I'm now part of the Insomnisquad! Though, admittedly, I now fear the fiery thing that rules the daytime skies.