I'm not sure there have been any studies on it but it makes sense that cognitive dissonance in humans would be a genetic advantage over other species. It allows us to acknowledge unfortunate truths like death and existentialism without driving us to insanity.

My personal cognitive dissonance is the optimism that we'll at least be able to slow climate change despite the mounting evidence to the contrary. If I lose that optimism, I would enter a very dark place in my own mind.