It could be dementia but you would notice signs during the day like confusion, wandering aimlessly, being easily startled. It's probably night blindness. Put him in a well lite room and see what happens when you leave the room. Whatever the case a trip to the vet is a good idea.
He doesn't get a lot of exercise because he has arthritis in every joint. The most we can get him to do is walk outside on the front porch and that's about as far as he can go. He is on the dog version of ibuprofen twice a day for it. We tried to let him swim in the pool during the day, but the next day after swimming, he can barely walk at all and it is difficult to watch. But yeah, he generally lays around all day so I'm sure he has some pent-up energy and his joints and body just aren't fit enough to use it.
I'm going to light up the room like you said and see if that makes a difference. We do keep it pretty dim in the family room at night. He's been to vet for various other issues recently. I will ask my wife if she ever mentioned that problem to the vet while he was there. The problem with my vet is that you can't even walk through the front door of the place without getting a $700 bill for something. If I asked them to run tests for dementia, I have no doubt they would gladly hit me up for thousands of dollars in fees, and I'm not spending that for a dog who has already exceeded his lifespan. I mean, I've got to save up for the next puppy.
One time on Shark Tank they had some people that were making hamburgers out of crickets... they actually passed out samples and if I recall correctly, the Sharks tried them. Now me personally.... not in a million, trillion years would I have tried a cricket burger.... 100 trillion years... but the thought did occur to me, for small dogs at least, like those Yorkies above (what a great great loyal, loving, not too much shedding breed--- and one day maybe for me)---> I wonder if anyone has ever tried to make cricket burgers for little dogs. Or cricket food for that matter. I don't think it would work for big dogs, waaay too many crickets. But I bet it's super-healthy. At least that's what those folks on S.T. said. Again..... not in a million, trillion years here.... BLAH.
Phew.... I just got LUCKY as all get out. Just now when I went to put her outside for her little afternoon romp around the yard, something caught my eye in the grass that wasn't supposed to be there. This thing was about an 18" snapping turtle. They move around this time of year to lay their I eggs I think, but I'll tell you what, those things can bite your hand off. I know muttley, she'd have seen that thing and went right to it. I don't even wanna think about what could have happened. We have a long leash for her, but I let her run while I'm trading because I can look out the window and can keep an eye on her. If I don't see her I'll call and she'll come back. But whew... I'm glad I saw that thing.
Close call. A couple of years ago I was trying to help a snapper across a road and was using a stick to guide it. It turned and bit the stick in half.
Hahahahahhaah. Yeah I know. I remember vividly when I was a kid, we were poking at one with a stick, and that thing flat out bit it in half. And my dog. god love her, I'm tellin' ya, she would have seen that thing and ran straight to it. I am so friggin lucky it caught my eye.