I can't help but wonder if this phenomenon isn't much like what I expereinced years ago when living day after day in a very negative environment. I was told I would often cuss in my sleep as though I were railing against those who were causing all the stress in the first place. No mystery there. I was surrounded by very inconsiderate people from whom I could not escape. I was an Army barracks back in the days when they would let in anyone not under investigation or awaiting sentencing, etc.

Could a lot of the negative sleep talking in this study be along the same lines? Perhaps a lot of these people have to deal with stressfull situations a lot, situations in which they have little or no control. It wouldn't surprise if this is, indeed, the case.