M.C.
I would try putting him to sleep earlier at night. Strangely, this may help him sleep longer and better, because he won't be so overtired. We started putting my DD to bed at 7pm at that age, and she began consistently sleeping through until her 5am feeding (I was still BF'ing), then she'd go back to sleep until 8 or so. It was very counterintuitive for me to put her to sleep earlier so she'd sleep later, but it worked. My husband and I even kept a chart for a couple of weeks, keeping track of when we put her down, when and how often she woke up, and when she was up for the day. Early to bed was clearly the answer, and helped her be happier and take better naps in the daytime, too!