Licensed veterinary technician here, this is something super common with older dogs. Unfortunately, the waking up in the middle of the night and pacing, agitation or confusion are all signs of dementia, or sundowners. There isn’t a lot that can be done for treatment, but the agitation and constant waking up can be alleviated with some prescription sedatives, with the appropriate conversation with your vet.

I had a pit bull that lived to 15 who would wake up every night at 2am and pace around the house in a circle for hours until she calmed down and went to sleep.

I always encourage everyone who has an older dog, especially larger breeds, to cherish every moment you can spend with your pets, because watching them get old and deteriorate is a bitch.