I had this problem with my son, because I split from his dad and had to move back home. He was used to sleeping in the same bed as me for about 7 mths. When I was able to move out, and he had his own room, he would get up several times a night and run to my room. I actually looked online for advice, and found the best one was just to get up everytime, put him back in his bed, and give him a hug and kiss. I also have a radio on in his room, do drown out any outside noises that might scare him. It took several weeks of being up every cpl hrs, but he now sleeps all night in his bed, and if he does wake up for some reason, as soon as i lay him back down, he goes right back to sleep. It can be a tiring process. I will admit after a cpl nights of being up every 2 hrs, i was ready to just let him get in bed with me, but im glad i stuck with it. Does he have a special toy or animal that he likes to cuddle with? That helps my son, esp when he is scared.