As the day progresses, you might notice that tasks that felt easy in the morning start to seem insurmountable by evening. The temptation to indulge in unhealthy snacks grows stronger, and decisions you could have made with confidence just hours earlier now feel overwhelming. This phenomenon is no coincidence—as the day progresses, our “executive functioning” abilities decline.

“Executive Functioning” is a set of mental processes that include working memory, flexible thinking, and self-control. We use these skills to manage our behaviors, make decisions, and achieve goals. Two related concepts, ego depletion and decision fatigue, negatively affect executive functioning, explaining why our willpower and decision-making abilities wane as the day goes on.

Understanding Ego Depletion and Decision Fatigue

Ego Depletion

Ego depletion is a term introduced by social psychologist Roy Baumeister, who conducted a groundbreaking study in 1998. The study explored the idea that willpower is a limited resource. Participants were divided into groups where some had to resist eating tempting cookies and instead eat radishes. Afterward, all participants were asked to work on an unsolvable puzzle. Those who resisted the cookies (using their willpower) gave up on the puzzle much sooner than the ones who were allowed to eat the cookies, suggesting that their willpower had been depleted. This study led to the theory that exerting self-control in one area can reduce the ability to exert it in another.

Thus, when you exercise self-control, whether by resisting a tempting snack or forcing yourself to complete a challenging task, you deplete your available willpower. As your day progresses and you continuously tap into this resource, your ability to exert self-control diminishes.

Decision Fatigue

Decision fatigue is closely related to ego depletion. It refers to the deteriorating quality of decisions made after a long session of decision-making.

Every decision you make, from what to wear in the morning to how to respond to an email, chips away at your mental energy. By the time evening rolls around, your brain is tired, and your ability to make sound decisions is compromised. This is why you might find yourself making impulsive purchases online late at night or reaching for that extra slice of cake. Add a bit of alcohol or THC, and your executive functioning and willpower decline even further.

Practical Implications

Some practical implications of our nighttime executive function decline include:

• Evening Vulnerability: Because our executive functioning is diminished at night, we’re more likely to give in to temptations, make poorer decisions, or struggle with tasks that require significant mental effort.

• Nighttime Snacking: A common example of this is nighttime snacking. People often have more difficulty resisting unhealthy foods in the evening because their willpower and decision-making capacity have been worn down throughout the day.

• Risky Decisions: Studies have shown that people are more likely to take risks or make impulsive decisions at night, which can be attributed to decreased executive functioning and decision fatigue.

How to Battle Our Nighttime Decline

The first step to battling our nighttime decline is to be aware of it. Realize that your brain isn’t as sharp at night as it is earlier in the day. Additionally, adopt these strategies:

• Prioritize Important Tasks Early—Since your willpower and decision-making ability are strongest in the morning, tackle your most critical tasks early in the day. Whether you’re making important work decisions, engaging in creative projects, or managing challenging conversations, doing these tasks when your mental energy is at its peak will lead to better outcomes. For example, I know that the quality of my writing is much better in the morning than at night.

• Establish Evening Routines: Create consistent evening routines to minimize the need for decision-making at night. This could include setting a regular time for winding down, preparing your environment for sleep, and avoiding tasks that require significant mental effort late in the day.

• Avoid Important Decisions at Night: If possible, defer important decisions until the morning when your executive functioning is restored. Or just revisit those decisions the next day before making a final decision.

• Incorporate Breaks and Rest – Just as a muscle needs rest after exertion, your brain needs regular breaks to recover from the demands of decision-making. Short breaks throughout the day can help replenish your mental energy. Use the Pomodoro Technique and Oscillate during the day.

Conclusion

Understanding that your mental resources are finite can help you take a kinder, more realistic approach to your goals and setbacks. Knowing about ego depletion and decision fatigue can empower you to structure your day more effectively. By prioritizing important tasks in the morning, reducing decision-making in the evening, and creating a supportive environment, you can combat nighttime decline and maintain your effectiveness throughout the day. Incorporate regular breaks, use if-then planning, and practice self-compassion to preserve your mental energy and stay sharp, even as the day winds down.