Strange sleeping changes in my Mom with Alz/dementia, Anyone ever experience this?

My Mom lives with my husband and I and is considered late stage I suppose. We use a hoyer to move her, she cannot speak much, and I puree her food. We can certainly get her to laugh though and she is a hoot ! I know she understands way more than we know of by her hundreds of facial expressions; but she has been in this stage for about 4 years at least now. A few months ago she was awake for about 48 hours give or take a few cat naps. For 2 nights she humms and laughs, kicks her legs fast, and says yahooo--weeeeeee etc. After two nights of this and pretty normal but awake days, she goes to sleep and sleeps for a solid day and night. She is now on her 3rd round of doing this in the past months. Today I got her up, bathed on toilet, dressed and got in her breakfast and fluids and then from 10am on she has been asleep. Its now 9pm. She opens her eyes, looks around for a split second and goes back to sleep. I am sure tomorrow she will be back to normal but this is awfully different, if not strange to me. She is fine, in no pain, happy and lovey when we snuggle cheek to cheek as always. Has anyone experienced anything like this? I give no medications to her for sleeping because in past years nothing seemed to work. She only takes bp meds and paxil. Thank you.