I'm in the same boat with my 8 week old. I just put up black out curtains...which seem to help recreate his night time sleep environment (we have good nights). I'm also eliminating all stimulation: television on in the background, any toys that buzz, bounces, lights up for 3 days, as BW suggests, to see if that is the problem. All activity is limited to observing the environment, listening to me talk and sing and watching my face, and sometimes I hold up one or two toys (nothing too bright or exciting). I know people say this is dumb because you make a baby that can only live in totally quiet environment, but guess what? I've been doing things the other way for the past 8 weeks, just to see him fuss at his toys, fuss at naps, etc. So at a certain point you have to accept the baby (I can't sleep with the TV on or people talking either). I know it is harder when you have younger children, but maybe that is something to try. My baby doesn't respond to shush pat either...I'm just working on getting as much daytime sleep out of him as I can, so the evenings aren't too tough. When all else fails, I stick him in the papasan cradle swing, which turns him off like a light switch. I figure, by the time he outgrows the weight limit, he'll be old enough to do PU/PD. Good luck!