Your brain's vigilance naturally peaks around noon then crashes in the afternoon, making you vulnerable to sloppy thinking and stereotypes. Sustained focus is impossible; mental fatigue forces your guard down like a plant closing its leaves at dusk.
Vigilance has its limits. After standing watch hour after hour without a break, our mental guards grow tired. They sneak out back for a smoke, and when they're gone, interlopers— sloppy logic, dangerous stereotypes, irrelevant information— slip by. Alertness and energy levels, which climb in the morning and reach their apex around noon, tend to plummet during the afternoons. And with that drop comes a corresponding fall in our ability to remain focused and constrain our inhibitions. Our powers of analysis, like leaves on certain plants, close up.
