It could be a growth spurt/new stage especially as it seems to happen to most of us at about 3 months of age. It seems that he is staying in a "light sleep" stage and not moving through to a deeper sleep? don't know if you are bf - but be careful of caffeine intake if you are. Also, maybe (?) keep him up for a bit longer during the day so he is more tired at nap and night time? My Rubystar is on the go most days and gets very tired when she needs to (!)