My dog normally comes with me or my daughter to bed about 9pm and sleeps until 6-7am. Past few nights she cannot settle. She's been barking a lot, constantly changing her position. She eventually crashed out for a bit on the floor around 3am. Then up again but I cuddled her and she settled again in my arms until I got up about 7am. She's now perfectly happily settled sleeping under the coffee table. While I feel like a zombie. She is getting on, she's 13 with arthritis for which she's on metacam. Last time she was like this the vet discussed euthanasia which I'm really struggling with. Is it dementia? I've read about sundowning which is what it sounds like. Any advice?