I so feel your pain! I went through this when my daughter was 3-turning-4.
This may seem weird, but have you tried to see what your son dreams about? My daughter had crazy nightmares for a while and would stall going to bed for hours some nights. When she finally revealed she was having nightmares, I was able to better help her. She went back to sleeping like a log soon after.

I loved it! I thought it was an awesome thing to do. Tupac had a lot of years in the music biz ahead of him. It's a shame his life ended when it did. This kind of gives fans a little of what we already knew we were missing..