I'm not sure how much research has been put into this, but from experience, I see the same things with my furry kids that I do with my aging family members.
My beloved 15 1/2 year old cat, Butler developed this quirk where he would scream his head off at night when we went to bed. When the TV and lights went off, he revved up. For many hours into the night, it would make us all crazy. He had health and mental issues before getting older so we figured it was just something he did.
Now my dog is acting weird. He is a 14 year old Australian Shepherd and at night he barks. Just one or two barks like every 20-30 seconds. For hours. We have a sound machine that plays rain showers for 45 minutes and shuts off after we fall asleep.
We have this because the dog snores like an old man and his bed is on the floor next to my side of the bed.
For the last month or so, the dog has been getting up about midnight after the sound machine shuts off and doing the bark thing until around 4:30 am. At first we checked for burglars, cats, dogs, opossums, anything that would set him off. Then we started closing doors to rooms with low windows and he would just stand in the middle of the living room or dining room and bark.
Go get him, put him back to bed, he'll get right up and start over. Let him outside, same thing. He just barked. For no apparent reason.
We haven't slept, we're exhausted, we're all snapping at each other and I'm starting to do klutzy things because my concentration is off. Throw in dieting and exercise and I'm a step away from becoming a serial killer.
I got this idea to leave on a night light, but have trouble sleeping with that tiny green glow from the smoke detector so nixed that idea. So last night, I thought to leave the television on in the living room, volume down. We're not sure if exhaustion finally caught up to us or it worked, but nobody remembers hearing him bark last night.
I always leave a TV on when I leave the house because all of our pets are rescues and I feel bad leaving them alone. Maybe it gives them comfort, but maybe it eases my guilt of leaving them alone.
So we'll try the TV again tonight, but turn it off Friday night (since we don't have to work the next day) and see if that's what did the trick to stop the barking or if we just slipped into a mini-coma and didn't hear him.
Fingers crossed, we all need the rest!