Unconsciousness in sleep. What do we do?

My father has a habit of taking sleeping pills everynight for last 10 years. However, on some nights we have seen him waking up at odd hours in night and do weird things as if he is drunk however he does not consume any alcohol. He if starts talking keep on talking without a pause and talk endlessly without stoping similarly if. He eats if starting eating too much...and then he sometime become so stubborn on doing something such as going out to bring something even if it is 2 in the morning and the market will be closed but he insit on driving and going to the market or insist of teaching someone to drive car and become so stubborn that he seeems out of our control and doesn not listen to anything Sometime he is even unable to stand properly or walk but just keeps on talking about random stuff without a pause. Please suggest waht kind of doctor can help us with this issue and what do we do?