He started peeing in the sink about a year ago and then stopped after being told it was unhygienic. He has recently started doing it again and has been "caught" a few times to which he acts as though something else is wrong, (a sore leg, or feeling sick). Might I add...he checks the coast is clear first. He's also been going to bed around 6pm and then wakens frequently throughout the night thinking it's morning etc. I have recently returned from travelling for a few months and have noticed a massive difference in him. It's quite concerning seeing the difference in him. Does anybody else's parents or grandparents do similar things?
My mother did the getting-up-several-times-and-thinking it is morning routine. She was at a moderate level then.
So these examples don't necessarily indicate late stage. An overall marked change in cognition and behavior is more significant. You know that grandad's dementia is going to progress, and there is nothing that can be done to stop that.
I wonder if grandad could have a uti? How long have these changes been noticeable? Did the people with him while you were gone mention that?
Keep an eye out for signs that he needs more help in certain areas and try to see that he gets it.
With any significant change in behavior it is wise to contact his doctor.