Hmm, this is a pretty good chart and is meaningful to me.  Earlier this year I think I got somewhere between "exhaustion" and "burnout" which was not pleasant, but seeming better now.  I think I'm still somewhere in the "difficulty concentrating" to "confused" region.

I am however concerned about the placement of "irritable."  As I get more anxious and confused, I generally get less irritable, because who am I to complain about you being stupid when I'm busy being stupid?   I find my irritability is somewhere near the "optimum" level.  Too bad for y'all when that happens. :)

I think the question that's generally not adequately addressed is whether it's good to be optimum at delivering on moderate demands, or sub-optimal at delivering on much more difficult demands.

Via: http://www.engineeringandcareering.co.uk/2014/10/catastrophe-and-engagement.html