Our brains can suffer from “mental fatigue,” just as our bodies can become physically fatigued after a long workout. What is so surprising about this phenomenon is just how little people appreciate the importance of mental fatigue and its resulting decision fatigue — even when making decisions that can be life-changing.
Decision fatigue helps explain why ordinarily sensible people get angry at colleagues and families, splurge on clothes, buy junk food at the supermarket and can’t resist the dealer’s offer to rustproof their new car. No matter how rational and high-minded you try to be, you can’t make decision after decision without paying a biological price. It’s different from ordinary physical fatigue — you’re not consciously aware of being tired — but you’re low on mental energy. The more choices you make throughout the day, the harder each one becomes for your brain, and eventually it looks for shortcuts, usually in either of two very different ways.
[Researcher] Heatherton’s results did much more than provide additional confirmation that glucose is a vital part of willpower.
The upshot? Don’t make important decisions late in the day or in the evening. Make your best and most important decisions before lunch. Whether it’s buying a car, a new house, deciding to switch jobs, or end a relationship. Make the important decisions in your life when you’re well-rested and the glucose levels in your brain are at their highest, typically first thing in the day. And eat a good breakfast to get the fuel your brain needs.
Decision fatigue comes from choice fatigue and shows limit of human mental power.