I only had one little boy hit himself in the head when frustrated and it was my grandson. He didn't hit others or do anything else to act out, he just started hitting his own head. I never saw anything like it before and was very concerned but I talked calmly to him when he started to do it and rubbed his back and tried to help him learn to breathe deeply and that soothing calmly when he became frustrated felt a lot better. He only did it for a few months.