My mom has been sleeping for 4-5 hours at a time. I had to wake her today so she could eat, and soon after she finishes eating, she fell right back into a deep sleep. She just started this within the last week. She was also prescribed Zyprexa 10mg, just recently (friday), for being down right mean & agitated, but the sleeping for hours began before she started taking Zyprexa. I'm confused to what is going on! Things are happening all of a sudden! Things are getting out of control with her! She went from being a half way decent person to be around to a mad, furious, frantic, distraught, hysterical, & a very agitated person just over night!.... Someone please tell me that her sleeping is just a part of her Dementia and nothing more, along with the sudden behavior change, because she is driving me insane, and my stress level is pretty high at this point... Too, I can't lie, when she does sleep, it's like when I had my small children, and when they took long naps, It was like, shewww, hells to the yeah!! I check on them sleeping and get some ME time all at the same time!!!
I am not saying this is happening to your mother but my father began sleeping more prior to his death which is normal we were told. Do not think this is what is happening, I don't want to frighten you.
I am with you however in saying nap time is wonderful, I tip toe around to keep it quiet and will yell at a telemarketer if they wake her! LOL!
From my support group, for some with dementia, this is very common. Dad having sleep apnea that he never did anything about while "fully functional" doesn't help - now he can't/won't break bad sleep position of side/belly which breaks the CPAP mask seal, & he lied about using it until Medicare took it back for non-usage (per the chip).
So yes, sleeping "constantly" isn't uncommon. Some folks theorize that their brain just gets tired from constantly trying to process what it no longer can process.