Try setting a fixed routine for ur child. Most importantly, make sure he gets enough naps in the day. No naps after 5pm. My child naps at 1130-1230 and 1600-1700. She will usual sleep by 8pm and wakes up at 7.30am.
there be many reasons why baby is not sleeping enough. sleep regression, not feeling full enough, over stimulation. for me a standard routine definitely helps alot in ensuring baby gets enough sleep!