Are insomnia and delusions common in elderly?

Hi doctor,

My father was alright one week ago. Suddenly one night, he could not get sleep, and that continued from that night. One or two days after, he started having some nightmares. He could not sleep, but he said he could see things, and he would consider them real. He kept saying something bad would happen, and doctors could not treat him. The last two days have been worse as he is claiming my mom of having an extramarital affair. But that only lasts during the night. In the morning, he understood that those were not real things. We saw a psychiatrist two days ago. He said it was anxiety and gave him some medicines. It is Lorazepam, Clonazepam, and some sleep disorder drugs. But things are getting worse. I need some help. Please tell me what it is and do we have a solution.