Some people have suggested he has ADHD but he is only three years old. Based on his behavior it seems like he is more hyper, innattentive, aggressive and stubborn than other children his age. He talks constantly, he is always jumping on and off the couches, chairs, or whatever else he thinks to climb on. He can't sit still for even ten minutes when we are eating dinner or watching a movie and when we go on hikes it seems like I can't do anything to keep him from climbing rocks and trees. He only sleeps for three to five hours a night and the second he wakes up he is on instant "go mode" and does not take any naps during the day. He does not listen to what I tell him or ask him, most of the time it seems like he is ignoring me. Is it possible that he has ADHD?