Make sure he's not getting any caffeine or too much sugar in the late afternoon/evenings. Also, make sure he's not getting too cold or hot. My daughter did this for a while last year and I was telling a friend and she mentioned maybe she was cold. My daughter would kick off her covers and get cold in the night then cry out for me. So one night I tried putting warmer pajamas on her and even socks on her feet and walah! problem solved. There could be lots of things going on, really. Have you asked him why he is waking up? Just a gentle, "what's wrong sweetie? are you cold, scared, sick, etc..." Something else is he may just want to be close to you. Maybe he doesn't get enough cuddles from you during the day? I don't know I'm just thinking of ideas so please don't get offended if I'm way of the mark here. I work all day and only have a few hours with my daughter each evening, then those are filled with cooking supper and chores, but I try to spend time with her and cuddle her, and each night before bed we cuddle together about 30 minutes before she goes to sleep. If you've tried lots of things I suggest you call his pediatrician. I don't particulary think it's a good idea to have him skip out on a nap. Most kids still need a nap through age 5.