I had the exact same problem with my baby. He would be up until at least 11pm, if not 1 or 2am. I started to realise that I needed to give him some sort of routine to break this habit. Since I have started actually planning his bedtimes things have really improved. I bath him at about 5:30 - 6 and then feed him and then into the cot. He cries for a while, but I just keep going in and comforting him and pulling the string on his musical toy until he goes to sleep. This takes from 30mins to 1 hour, but is improving. The biggest breakthrough I had was to realise I needed to put him into bed the moment he exhibited any tired signs. Otherwise I miss the window of opportunity and he gets overtired and won't sleep. The problem is, an overtired baby can seem wide awake, or windy, or hyperactive, or anything other than tired. Watch very carefully and put him down as soon as he grizzles or yawns etc. Anyway, you've probably solved your problem by now as your post is quite old, but maybe this will help others too! A really good book I have discovered is "The No-Cry Sleep Solution" by Elizabeth Pantley. It gives good advice on using routines, etc to help with sleep problems.
Jessica, VIC, Max 24.08.03