Photo by Logan Ingalls.
In its (very long) explanation of this phenomenon, the Times reports that experiments have demonstrated a "finite store of mental energy for exerting self-control". Each decision you make and the more choices you make throughout the day, the harder it gets for your brain to continue to make decisions. The result is that towards the end of the day when you're low on mental energy, you're more likely to either give in to impulses or avoid making decisions altogether. The worst part is that, often, none of us are aware of how mentally tired we are just from all the little or big choices we make throughout the day.
Researchers theorise that low glucose levels later in the day may be responsible for the poor decision-making as well.
The takeaway, if you want to make the best choices: eat a good breakfast, try not to schedule endless back-to-back meetings, and reserve your biggest commitments and decision-making times before the afternoon, if possible. Knowing your best and worst times for self-control and decision-making may help prevent a lot of mistakes or regrets.