My husband is sleeping so much. Is it the Parkinsons?

He is 70 years old and was just diagnosed a few weeks ago, but the more we learn we have figured out he has had this at least 6 years. From reading I have seen how much he has improved with medicines and therapy in these last 3 or 4 weeks but he is still sleeping alot. He gets up for therapy(twice a week physical and speech) and to eat then lays back down. He'll get up and talk to me maybe a couple hours out of the day. He seems to have a good time sleeping he laughs and acts out stuff like trying to walk or fix things. Is this all normal part of it? I miss him and it gets lonesome. I think he is so much better but then he's still sleeping about 16 or more hours out of the day.