It's a reasonable assumption, but I don't think that's all there is to it. Prison is generally not a comfortable place (where I live, lack of windows is standar

It's a reasonable assumption, but I don't think that's all there is to it. Prison is generally not a comfortable place (where I live, lack of windows is standard, for instance, even in multi-person cells). And yet, people who experienced solitary are all seem to be putting an emphasis on the lack of human contact. They are not begging for books or windows. I got an impression from the article that it's at least somewhat common to have access to books and even TV, and it's still just as torturous. They are begging to be allowed to spend time with other humans.