What's the mechanism for being mentally tired?

Question

I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a perceived lack of mental concentration?What exactly is the mechanism that makes my brain feel worn out, or at least gives me the perception of my brain being worn out?

Answer 1

Hey! Great question! I know exacrly how you feel. Without getting too indepth, the reason your brain physically feels tired is because it is. For decades, neuroscientists have known that the adult brain had a limited capacity for focused concentration, approximately 45 minutes. Multiple studies on concentration, mental acuity, and overall mental function have found that after about 45 minutes of focused, concentrated effort, the neurons and their supporting microglia are fatigued. At that point, they have run through enough of theie stored fuel (oxyegn, glocose, etc.) that they are no longer able to maintain their peak activity levels. This is why most classes are about 45 minutes long. It is also why most movies, drama, action, or otherwise, will have small bouts of comedic relief every 45 minutes or so - to help give our overstimulated brains a bit of a breather before more heavy plot stuff.

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