I play mostly $25 NL HE Ring Games on Party. I find that I make most of my money between 11:00pm - 1:00am
Pacific. Partly this is because I don't start playing until 8:30-9:00 and it takes a bit of time to build up a comfortable stack which I can then leverage into more $$$. Also I think it's because people start getting tired and they are "trying to win their money back." Hence, a lot of loose action and stupid play.