My dad is 63 and recently started going to bed before 8 pm and sleeping until 6 am. He said he gets bored so just goes to bed. He is not depressed. Last night he got up at 10 and called my mom asking where she was. She was in her room. At midnight he went to her room and woke her up, saying he couldn't see her. His behavior is unusual. He also asks questions that we have answered several times already. Could these be early signs of dementia? It runs in his family. Thank you!