Father with Alzheimer's in deep sleep and will not wake up. Is this typical of very end stage?

I've been looking for "end signs" for 5 years now..... only time will tell if this is a new trend or not, it's better to just take it one day at a time.

My Mom has had sleep issues for a while and now is on Melatonin 5mg at night. Even with that she still has 1 day/night every couple of weeks where she is has had no naps and is alert all night. The next day she is exhausted and we just let her sleep. If figure she normally is awake only about 8 hours total a day, so being up 24 hours will take a few days to catch up. The first thing I ask when I get to the NH is how did she sleep last night? So I know what to expect. So he might just have been really tired from being up all night. Also Mom is on low dose tramadol which can mess up sleep. So you could revisit his meds to see if there might be some side effect.

When mom becomes lethargic it is sometimes a sign of illness or a UTI

My MIL with dementia (we think it's Lewy body) lives in a nursing home. You can visit her one day and she's alert and mumbles all day long (you can't understand what she's saying). The next day she can't open her eyes even when she's awake. On other days she's asleep and you can't wake her up and we think it's over and the next day she's alert and babbling. It's a day to day thing.

I am not sure what is typical. My mom is stage 7 and on hospice. She never sleeps deep like that. Can you check at see what meds, at what dosages, at what times were administered?