He broke the window becouse of a bad dream and hurt himself.O GOD,something like that happend too me once,l was really tired one day and l slept earlier then l usually sleep and l had a pretty strange dream,like a King kong was on my window and he was screaming,l heard the sound a saw it and he wanted to hurt me,l ran out of my room and wanted to hide in the living room,and then king kong was in the living room and l just broke the window to escape from him,but l realized l broke the mirror in my room for real,l cried for two weeks from pain.