I write pretty much all the time, day or night. I prefer night writing
because the phone rings less often, and I can blow through a lot of work
without interruption. Lately, though, I find that I do get a little tired
come around 2-3 a.m., which I didn't used to, so some of it has switched back
to daytime or early evening. My advice is to just find what's most
comfortable for you as a time to write, and stick to it.

jms