Sleepless Nights

We started giving Carson melatonin at night to help him sleep. It's so hard for him to settle down and fall asleep. He used to be in bed for hours before he would finally fall asleep. The melatonin has made a huge difference! However, he wakes up almost every night at 3am and he is wide awake. He is hyper and so so so loud!!! He doesn't cry but just yells so loudly. His sisters room is just across the hall and he sometimes wakes her up. I go upstairs to his room and attempt to lay with him. I will tell him it's still night time and he needs to lay down and go back to sleep. I tell him to be quiet and close his eyes. He looks at me blankly and gets louder. He is so unreachable. He doesn't comprehend anything I say. I eventually leave his room and he stands at his open door yelling louder and louder. At this point every one in the house is awake. This is becoming an every night occurrence. I don't know what to do or how to get through to him. I don't know how to parent a child that doesn't understand anything I say to him. Things were going so well for awhile and now it's like we are back to the beginning. All I can do is pray for strength and patience and hope that this too shall pass...