Currently I'm living alone and working from home. I have no externally-imposed schedule. This is probably the closest I'll ever come to a completely natural sleep cycle (though I go out dancing a lot which messes it up.) I've found that at 3:00 or 3:30pm I have the strong desire to take a nap. I sleep 20 minutes and I'm back to work.
I've always liked naps, but now the desire to sleep at 3 is so regular I schedule it into my work day. I'm also getting a daybed or couch in my office at Carleton.
I just read this article that says we should take a 20 minute nap 8 hours after we wake! It's interesting that that's exactly what my body has wanted to do.