I can't get 93 yr old dad to get out of bed during daytime hours. Advice?

He will stay in bed until 3-4pm if someone isn't here to remind him that he can't sleep all day. The problem is by sleeping all day he doesn't sleep well at night, then paces the house (which is a small brick ranch) and then keeps coming into my husband's & my bedroom waking us up, confused and wondering where "everyone" is (it's just the 3 of us living here; he keeps forgetting mom is in a nursing home), why we are sleeping, etc. Very worried about this! My husband is the lightest sleeper I've ever known and this late night activity keeps him awake.