Constant 😴 sleeping.

That is not a remarkable amount at all IME. Some PWD sleep 20 hours a day, especially in stages 6+

this article will explain: https://www.alzra.org/blog/sleep-changes-in-dementia-why-do-people-with-dementia-sleep-a-lot/

thank you SDianeL for the article. It provided more and better explanations than any of DH’s doctors

My DW's baseline sleeping is 10-11 hours at night and 1-3 hours napping. She will sometimes sleep 16-20 hours in a 24 hour period.

late stage 6 here, these sleeping bouts come on if DW has not had much sleep in the past few days. Like her batteries deplete and she just powers down for 23-36 hours and recovers. I addressed this by putting in a strict bedtime routine and sticking to it. Meds at 8 pm, includes sleep aids, cut off water intake, leave her alone in bedroom w/lights on, no noise (I can still monitor her). Most nights, she climbs into bed on her own, usually around 10- pm or so. I sneak in, change her if needed, and pull covers over her, turn lights out and leave. I usually get to be around midnight. Routines can work.

I am so sorry, your SO is peacefully sleeping now. It’s sad and inevitable and I am not looking forward to the day. My DH drops off at all hours of the day for around 3/4 of an hour then is awake for an hour or so then sleeping again, sleeps from 9pm till 2am at night and then wanders around the house for a few hours then restless sleeping until about 5am and is up wandering again. I’m exhausted!

Very sorry for your loss, Bob.

I don't believe anyone mentioned - although it is common at later stages, I would recommend ruling out any medical cause by having a urinalysis and bloodwork for a start. There are a lot of illnesses - even a virus - that can cause extreme fatigue.