Where I live there are some regulations about leaving your pet alone. I don't know the details but I guess it is ok to leave a dog alone for a couple of hours, while fishes probably can be left alone for days as long as they are fed.
Anyway, I rarely leave my dog alone for more than an hour so it is not a problem anyway but I was thinking about the purposes behind this legislation and for dogs it is quite simple, they need to take a walk every few hours and they are pack animals that don't like to be left alone.
BUT, every night when I sleep I leave the dog "alone" for 8-9 hours. Obviously this is fine because the dog mostly sleeps during the night anyway and, here is my question: does a dog who wakes up in the middle of the night and realise that its human is in the house feel alone because there is no interaction between human and dog? Or is it satisfied by being able to smell and hear the human?
And a second question: the answer to my first question is quite obviously something like "most dogs are happy with being near a human during the night and don't need any direct interaction with the human to feel good" but that might be because dogs, like humans, sleep during the night. However, I frequently take a 3-4 hour nap during the day when my dog is supposed to be awake and active. Is this "cruel" to the dog? The (sound) idea behind the legislation I mentioned in the beginning is that dogs need company and stimulation and, if I sleep during the day, I obviously can't provide my dog with that.
(I can add that my dog usually sleeps on the floor next to my bed when I take my naps. It doesn't do anything the indicates it is sad, annoyed or something like that. It might look bored but that isn't really connected to me sleeping: it looks bored now when I write this question because I don't play with it or stimulate it in any other way. But that's a dog's life, I guess!)