My Father In Law Is Taking Namenda, Aricept, Rivastigmine, Zyprexa

My father in law is taking Namenda, Aricept, Rivastigmine, Zyprexa and Cymbalta. He has not been feeling well and complains of being so tired he can't get out of bed, is unable to even leave the house to go grocery shopping of anything else. I am a nurse and I am very worried that he is on so many medications. Could all these meds be the problem?