Are Behavioral Issues With A Child Staring At You While Being Reprimanded And Them Having Nightmares A Serious Concern?

My 6 year old is having so many behavioral problems since he can talk. he blankly stares at you when you talk to him if he is in trouble. and will stare continuously until you have to leave the situation. he also has a hard time sleeping at night saying he is having nightmares about something but i am not sure what he means by it.