My son did this when he was little. The best advice I ever got was not to wake him or touch him. The doctor told me to say his name and then start telling him a story about something else. Example...Remember the time when we had all those puppies and they would lick your face, remember how it tickled, you would giggle, that puppy is licking your face now, he so cute. Once he had taken what I was talking about and dreaming about it instead, I would rub his back and help to calm him, kiss him on the forehead and leave him to a better dream. Even though they are asleep they can hear every word you say, if you over react and try to wake them then you become a part of the night terror. There were times when he would wake up the next morning and tell me about the puppies licking his face. He's 18 now and still dreams heavily.