What is a typical schedule for a home health worker?

My father has Lewy Body Demential. My mother lives with him and takes care of him. My mother are at night starting at around 6 or 7pm. My mother uses a walkerand she has to undress him, put a diaper on him. He often wets himself and will go to her for help. She puts him to bed and he cant sleep and wakes her up repeatedly all night long. I am going to hire home health care but I would be interested in a typical schedule might be for the worker. My mom really needs someone from 7 to 7am. Does night time cost more? are they allowed to work 12 hour shifts? Thank you