Mom was diagnosed with dementia 3 years ago. She was fine until last week, now all she wants to do is sleep. Can anyone tell me why?

My mother is doing the same thing. But we do walk the dogs every day for 20 minutes. She still bathes / dresses herself. Thank you God. But she's developed this obsession with touching her ear and using more napkins than any human needs. I've asked if she has an ear ache. She says no. She's stopped wearing make up. For the last month. She sleeps with light on and of course Foxx News. A year ago, she was driving every day and working part time. She is probably stage 3? Maybe 4? Short term memory gone. Constantly repeats.

I don't have a lot of experience with dementia & sleeping because my Mom is the energizer bunny, but I would check her medicine and check to see if it could be depression or possibly an infection/illness.