My loved one has Alzheimer's and he has this up and down manic depression. Has anyone else had this experience with Alz?

When he's up it's almost like the like man I know is back. He remembers football game details, etc. Each time he's down there's lots of sleeping (he's making up for the non-sleeping on the high days and nights) and each down demonstrates as really receding more and more into himself. Curious if this is common. Internist says it's common. What are your experiences?