Sleep is an interesting thing. I'd prefer a nocturnal cycle because I find the night more interesting to be awake during than the day, unfortunately large majorities of the world disagree with me, hence the whole "everything is open during the day" thing.
I'd love to try something like the Uberman sleep strategy, where you take a half hour nap every four hours, but I've read that this can kill you mentally and deteriorate physical health.
As for naps, I almost never nap. I nap during the following circumstances:
1) When ridiculously tired
2) On vacation
3) After doing physically strenuous work for most of the day
4) After confirming that there is absolutely no better use of my time than to sleep
5) when I am waiting for something to happen in a few hours and condition four is already met.