On the way to work, you stop for your usual coffee. As you walk through the door, 20,000 cups of coffee are laid out all across the room, covering the floor and tables. Somehow, you need to choose the one you’ll like best.

Tasting all 20,000 is impossible. So after trying a few, picking your favourite, and going on to work, you may not feel too satisfied with your chosen coffee. With so many options, there’s no way to know you chose the best- the very next cup could have been even better. (20,000 sounds absurdly large, but that’s fewer options than some big-name shops offer.)

During the day there are only more choices and decisions to make; from the best way to get your work done, to meetings, to the quickest way home. By the end of the day there probably isn’t much room left for thinking about anything difficult, such as starting that project you’ve been putting off or resisting the cake in the cupboard.

Although we hate not being able to make our own choices, it turns out that having too much choice is just as much of a problem. Making choices, major or minor, drains us. It leaves us less able to resist impulses or see through illogical options. Psychologists sensibly call this decision fatigue.

One example of decision fatigue is shopping on a tight budget; the effort needed to consciously weigh up every purchase makes it harder to resist other impulse purchases later. In laboratory studies, people who had to decide their preferences for products on a list later found carrying out maths calculations or resisting procrastination more difficult than people who merely had to think about those products. Other examples have far larger consequences. Researchers Danziger, Levav, and Avnaim-Pesso studied how judges responded to prisoner’s requests, such as seeking parole or asking to have a tracking device removed, during a work day. In the morning, the judges accepted about 2/3 of requests, but then their rejection rate dramatically increased throughout the morning. After lunch, however, the judges again accepted about 2/3 of the requests.

Decision fatigue is connected to how we understand willpower. People generally fall into two camps when talking about willpower; some see willpower as a muscle which must be used otherwise it atrophies. Others see willpower as a finite resource, like a petrol tank which runs out with use. Research at the moment suggests that both ideas are true: willpower can be developed over time, but in day-to-day life it both depletes and recharges quickly. As our everyday life is filled with larger and larger streams of information, options and customisation, we are required to make far more tiny decisions each day, which increases decision fatigue.

Most of the ways to reduce decision fatigue sound sensible. Advice generally includes making your most important decisions at the start of the day; avoiding situations where you commonly make impulse decisions such as online shopping; and deliberately limiting the amount of decisions you need to make. However, a slight problem with all of those things is you have to choose to do them. So to reduce decision fatigue, you initially need to add more decisions.

One way many people reduce decision fatigue is by putting less-important aspects of their life on autopilot. Consider Steve Jobs’ trademark jumper, or Barack Obama’s duo of suits; both men removed their need to make daily decisions about clothing, to save energy for more important decisions. Athletes can put nutrition on autopilot by eating the same meals and supplements at the same time each day. People can also change their shopping habits, their work environment, or their computer use to limit how many decisions those parts of their lives create. Another way people reduce their chances of decision fatigue is by creating routines, such as “in situation X, I will always do Y”, or “to get to place A, I will always drive using route B”. Every situation which only has one answer is another saved decision.

The study of how individuals make decisions is named decision theory (or decision science). Unlike its more famous relatives such as game theory and cognitive psychology, decision theory is usually only taught at university-level. Although some high schools have successfully trialled decision science teaching, supported by nonprofit organisations such as the Decision Education Foundation, the interdisciplinary nature of decision theory can block it from receiving a place on many school curricula.

To me, this is unfortunate, because understanding how we affect and are affected by the world we live in should be a priority. Many parts of everyday life place more demands on us than we think, or tax our ability to focus on tasks or keep our brain at its best. Learning how we think, what impedes our thinking, and how to use our brains most effectively, is some of the most valuable information we can be taught.

More resources on decision science:

The Harvard Centre for Health Decision Science, which has good decision-making resources that also discuss cognitive biases: http://repository.chds.hsph.harvard.edu/repository/collection/resource-pack-decision-making-biases/

The Decision Education Foundation: https://www.decisioneducation.org/

A guide to limiting decision fatigue: http://www.asianefficiency.com/productivity/how-to-beat-decision-fatigue-the-ultimate-guide/