Five Ways to Limit The Impact of Mental Fatigue & Improve Decision-Making

March 17, 2016  Posted in: How To's, Stress Reduction, Uncategorized, Warning Signs

Most people would agree that they make poor decisions when they are stressed, hungry, angry, lonely or tired.   Recently, scientists discovered the very act of making decisions tires the mind and makes it more difficult to exert self-control.  When mental fatigue sets in people make impulse decisions, give into temptations or simply do not make a decision at all.

Dr. Roy Baumeister was one of the first researchers to discover decision-making fatigue.  He was doing research about self-control when one of his researchers commented on the fatigue she felt when choosing items for her wedding registry.  Based on her observations, the researchers devised a study about the impact of decision-making on self-control. They purchased some items from a department store and then told one group of college students that they could keep one item after deciding which object they liked the best.  Another group was only asked their opinion about the items.  Then, all the students were given the task of putting their hand in a bucket of ice water.  The “decider” group gave up in an average of 28 seconds while the non-deciders gave up in 67 seconds.  This astounding result suggested to Dr. Baumeister and his team that decision-making depletes our mental resources.

Over the next few years, a series of experiments replicated the results suggesting decision-making is a limited biological resource that uses the same mental energy as willpower and self-control.  One study conducted is of particular interest to lawyers.  Researchers in Israel reviewed more than 1100 parole decisions made by judges over the course of 10 months. The researchers found that in the morning or after a meal break the judges granted favourable rulings 65 – 70% of the time.  Whereas in the last three cases of a session, prisoners had a 10 – 15% likelihood of receiving a favourable ruling.

The study revealed that the biggest factor in whether or not a prisoner received a favourable ruling was early in the morning or after a rest and meal break – not their sentence, ethnic origin or crimes. The only factors that seemed to buck the trend were if the prisoner was a repeat offender or had no real plan for parole.  Then, they were denied parole in practically every instance.

The study does not mean that judges are making irrational choices or bad decisions.  The fact ethnicity played no part in their decision-making implies that the judges were treating each prisoner equally and concerned with rendering a just result. However, as the cumulative length of the session went on judges were more likely to render more negative rulings and the study supports the theory of decision fatigue.

Based on the research, here are five ways to help you make good decisions:

  1. Awareness:

Unfortunately there is no feeling associated with mental fatigue. When you get mentally fatigued you take mental shortcuts like making self-indulgent choices, impulse decisions or letting others choose for you. Becoming aware of the impact of decision-making fatigue and what you do when you are depleted is the biggest ally for making good decisions.

Making good financial decisions is one practical reason to be aware of decision-making fatigue.  In one study, real life purchasers were given several options when choosing options for their vehicles.   They were diligent in picking out the first options but when it came to later choices they simply chose the “standard” option essentially letting the salesperson pick for them.  The standard option was usually more expensive than the basic option and people ended up paying thousands more for their vehicle than they had to.

  1. Make Important Decisions after Eating and Rest:

Researchers discovered that eating or drinking replenishes the decision-making ability.  The brain needs glucose to maintain good decision-making ability.  When we are mentally depleted we opt for sugary foods to give us a jolt of glucose in the blood.  This does not mean you should always opt for sugary foods when depleted. High glycemic foods metabolize faster and leave you in a much worse state than before. Healthy eating restores glucose in the body for a longer period of time and makes your decision-making better.

Sleep and rest restores decision-making abilities. There are numerous studies that show humans need eight hours of sleep a night.  Many of us are pressed to get that much sleep for a variety of reasons.  In order to improve your sleep, establish a routine of going to bed at the same time every evening (even weekends) and spend at least one hour without a screen in front of you (even an e-reader). If you do not get enough sleep, be aware of the limitations of your decision-making abilities and take breaks before making large decisions.

  1. Establish Routines

Making fewer decisions by establishing routines around daily activities limits mental fatigue.  It is rumored that Barack Obama takes the research into decision-making fatigue very seriously.  He develops routines around his daily activities like meal times and exercising to save his mental energy for really import decisions.  Some people establish a routine of wearing the same clothes for each day of the week. For me, choosing what I will wear for the next day in the evening limits the decisions I have to make the following morning. Your routines do not have to be about exercising or the clothes you wear but choosing a routine that works for you will make for better decision-making.

  1. Develop Habits Around Temptations

Develop habits around temptations that will not put you in the position of choosing or resisting in the moment.  Researchers found that resisting temptations uses the same mental energy as decision-making. They also found that people who have the best self-control spend less time resisting urges because they develop habits that do not put themselves in situations where they are tempted.

There is another study of over 2000 people who made resolutions that supports this research.  Many people failed and did not continue with their resolutions.  Interestingly, the vast majority of people who kept resolutions still had failures but they treated the failures as setbacks. They identified crucial moments and had a personalized strategy to create helpful habits to avoid the situation in the future.

  1. Self-Forgiveness

Self –forgiveness is an important factor for good decision-making. Feeling guilty seems to use the same mental resource as decision-making and self-control.   In one experiment, dieters were instructed to eat a donut and then do taste tests of various candies.  After eating the donut, the researchers compassionately told one group not to feel guilty about eating the donut and nothing to the other group. Next, the dieters conducted the “taste test”.   Researchers found the dieters who were told not to feel guilty ate 40% less candy than those who were told nothing.  This finding is consistent with other studies that show self-forgiveness is an important factor in addiction recovery.


If you would like to speak to LAPBC counsellor on a strictly confidential basis, contact us at 604.685.2171 or 1.888.685.2171 or  ( info (at) lapbc (dot) com.


Baumeister, Roy and John Tierney, Willpower: Rediscovering the Greatest Human Strength, New York: Penguin Group: 2011

Danziger, Leva and Avnaim-Pesso. 2011. Extraneous factors in judicial decisions. PNAS

McGonigal, Kathleen, The Willpower Instinct, New York: Penguin Group: 2012

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