Why do children misbehave when they are tired?

We all know what it means to be tired, because it is a feeling that we often experience. When we carry out any activity for a certain time, whether it is physical or mental, and even after experiencing intense emotional states, we feel tired, even exhausted. We could define fatigue as the lack of strength after performing physical, intellectual or emotional work. Boredom, unhappiness, disappointment, weariness, tedium or annoyance can also leave us exhausted.

In any case, tiredness has curious effects on our behavior, which are reflected in a greater difficulty in maintaining self-control. This is very easily perceived in children, because when they are tired, either after having carried out an exhausting activity or as a consequence of boredom or disappointment, they tend to carry out actions that annoy us. Or, put colloquially, they tend to “misbehave”. What is this effect due to?

Brain control tower failure

The reason is found in the functioning of the brain, so let’s start talking about it. The brain is the organ of thought where all our behaviors are generated and managed. It is structured in different zones, which fulfill specific functions within the overall task of this body. Behavior control is specifically in charge of an area called the prefrontal cortex. It is located in the most anterior part of the brain, just behind the forehead, in the most superficial layers of neurons. Hence its name.

The prefrontal cortex is responsible for managing the most complex cognitive tasks, which are grouped under the name of executive functions. They would come to be like the control tower of an airport, whose function is to order all air traffic so that it flows without difficulty but in a flexible way, not static, so that it can be adapted to any situation that arises: a change in the weather conditions, a flight delay, etc. In other words, they serve so that we can control our behavior.

Executive functions include various aspects, such as the ability to reflect and plan; to make decisions based on the reasoning we have made; and to rationalize and manage our emotional state, among others.

Also included in this group is working memory or operative memory, which is the set of processes that allow us to temporarily store and manipulate information to carry out complex cognitive tasks such as language comprehension, reading, mathematical skills, learning or reasoning. Not forgetting cognitive flexibility, which is the brain’s ability to easily adapt our behavior and thinking to changing, novel and unexpected concepts and situations, or the mental ability to think of several concepts at once.

What does all this have to do with tiredness and how does it affect the behavior of adults and children? Very easy. Although we like to boast that we have a very large brain, the reality is that it only represents 2 or 3% of the total mass of our body. And yet, it consumes no less than 20 to 30% of metabolic energy! A brutal disproportion.

And of the entire brain, the part that consumes the most is precisely the prefrontal cortex.

When we lack energy we mess up more

When we are tired, the metabolism tends to spread out the usable energy, thus reducing the energy available for the prefrontal cortex to perform its functions with maximum efficiency. In other words, it is more difficult for us to reflect, plan, decide, manage emotions and store and manage information because the prefrontal cortex has less fuel to function. And this also makes our thoughts lose flexibility and become more rigid. As a consequence, we lose the ability to self-control behavior.

Hence, when we are tired we tend to say things that we should not, that we know can hurt loved ones. And we do it because our brain has a harder time controlling itself. Because executive functions, the control tower of our behavior, work less efficiently.

And the same thing happens to children. Despite knowing that there are things that they cannot do or that we do not let them do (and that they know well), when they are tired the probability that they will do them, that they “behave badly”, speaking colloquially, increases. Simply because they have a much harder time maintaining control of themselves, like adults, because their prefrontal cortex does not have all the necessary energy.

Boredom has a similar effect to tiredness

Interestingly, when we are bored, disillusioned or tedious, something similar happens, although the origin is slightly different. It turns out that when we’re unmotivated, the brain also receives less energy, so the prefrontal cortex can’t function at its best. Or, seen the other way around, motivation increases blood flow to the brain and, with it, available energy, which generally improves the functionality of executive functions.

For this reason, when we are motivated we normally reflect, plan, decide better and we can manage our emotions much better. Although without going overboard, since an excess of motivation can hyper-energize the brain, reducing the efficiency of its operation, as a recent study has just shown.

And another curiosity: being tired has a good side. After having done a strenuous activity, we also tend to be more creative, because when self-control fails, ideas arise without filters, or with fewer conscious filters.

David Bueno i Torrens, Professor and researcher in the Biomedical, Evolutionary and Developmental Genetics Section. Director of the Chair of Neuroeducation UB-EDU1ST., Barcelona University

This article was originally published on The Conversation. Read the original.