Disclaimer: I'm not a researcher in this topic and I have no idea what I'm talking about, just putting my thoughts here

I think that depends on how you define stress? The brain is all electrical signals, so from this simplistic point of view there shouldn't be such thing as "stress", but from my understanding the connections, even though electrical, produce chemical by-products which have to be "flushed away" by the gray matter. This and just human experience suggests brain can get "tired".

However, I don't think the societal problems throughout history had much relevance to the individual stress brains my experience, but more caused by cognitive dissonance when you try to put two conscious beings together, as every brain is different so produces different outputs to same input. Additionally, we still are very much driven by our animal instincts, even though we like to pretend we've "ascended" and have free will.

Now the question is, where can we evolve from here? What evolutionary pressure is there to evolve? We've pretty much peaked as lifeforms, we can dominate any and every environment we want to the point of being detrimental to the Earth itself.

Also this highly scientific documentary I re-watched recently called "Idiocracy (2006)" suggests that higher brain function doesn't necessarily increase the chance of passing genes along, and I tend to agree.

If you want to do research, usually the first thing to do is refine your research question up to a point where it becomes relatable to the scientific state of the art and where it becomes clear how to test / evaluate it. I don't think you are there yet.

A couple of things I'll point out. Evolution occurs at the level of population genetics, and it's not concerned with finding a stable state for any characteristic, at least not directly.

But more importantly to your question, the way we define society right now, or agree to be governed, is not a given, and it's not a fundamental quality of the universe or its reality.

Society in this point in time is an artifact of this point in time, and the accumulation of our historical and cultural works. So what is the societal problem, and for whom? How is the meaning of such a problem transferred from a social phenomena (resource allocation) to a biological one (stress responses, like cortisol homeostasis) to one which affects populations (propagation of some phenotype or genes)?

You have to connect sentience and cognition in a direct line with biological stress responses and evolutionary genetics, and its effect on brain evolution. It's an interesting question, but it depends on how it is decomposed and framed.

One of the ways I like to look at it is, humans have the unique ability to look into the past, and into the future. With this ability and the help of language, we are able to replay past experiences (good and bad) and make predictions on the future (plan forward, avoid things that hurt us before etc). This can cause “stress” or “pain” on the brain/person when those thoughts are negative. As things normally do, this “stress” can vary from person to person, depending on their makeup, life experiences, habits etc.