If someone is sleepwalking, leave them alone. They will be seeing things as they are in their dream, not in reality. You could be a zombie, a lover, etc... Who knows what might happen if you try to interact with them. The best things to do for someone who is sleepwalking is to make it so they can't leave the house, hide the car keys, and stay away from them. Get them an appointment with a doctor ASAP for medication or a sleep study to get this sorted out and make it stop happening.