Does the brain get tired? (Yes or No)

Who has not ever felt that they are mentally tired, that they cannot focus or concentrate?

In this article we’re going to answer the question ‘’Does the brain get tired?’’ We will discuss the relationship between physical and mental fatigue and why we tend to feel tired after work hours.

Does the brain get tired?

Yes, the brain can become overloaded with energy. And this can be expressed in mental fatigue.

Many of us spend a large part of the day in front of the computer. Reporting, writing, watching videos, and answering emails.

However, despite sitting for a long time, when you come home after work many times with the intention of doing something else, you find that you are exhausted, and not only mentally, but physically as well. Something unusual considering how little you moved during the day.

Some types of tiredness seem more deserved than others. It’s common to feel tired after running, but after answering emails? Well, according to Dr. Steven Peinsilver, director of sleep medicine at Lenox Hill Hospital, mental fatigue is real.

The brain is only 2% of people’s body weight. However, this percentage doesn’t correspond to their role in the functioning of the body.

Sometimes it acts from the shadows, but with its chemical power, the brain directs the vast majority of processes that keep us alive (digestion, movement, etc.), in addition to those that characterize us as human beings (speech, reasoning, etc.).

With so much activity, it’s logical to think that the brain could reach exhaustion. The sensations we have are very different from those we notice when fatigue is muscular, but they also clearly indicate that something is not right. 

Does the brain get tired like the muscles?

The composition of the brain is not similar to the muscular one. Its structure is made up of neurons; cells specialized in transmitting information through chemical messengers and electrical signals. However, although it is not a muscle, the brain also needs energy.

When we are at rest, the brain can consume between 20 and 25% of the total energy that the body of an adult needs to function (around 350 or 450 calories). In children, the percentage is even higher: it can exceed 60%. This makes it the most energetically demanding organ in the body.

Its main fuel is glucose, which is converted into a complex organic molecule (ATP) that cells transform into energy. The problem comes when the brain consumes all the glucose available to it. Then the action of dopamine, the neurotransmitter responsible for motivation and attention, also decreases.

As a study published in 2018 showed, although it doesn’t tire like muscles, when the brain works hard it can be chemically exhausted. In this way, we will lose the will and the courage to continue with our occupations.

Do we consume more energy if we think a lot?

The brain is designed to automate tasks, it needs to invest a great deal of energy when dealing with new situations or unfamiliar information. Therefore, as soon as possible, it abandons the so-called executive functions (necessary for making decisions and solving problems) and puts the automatic mode.

For example, learning to play an instrument or devise a master chess move will require more mental effort than those routines that we carry out daily. However, it doesn’t have to be the cause of fatigue.

In reality, the energy that the brain consumes to deal with new situations or to learn a new task is very small compared to what it uses globally to carry out its many functions in the body. Don’t forget that this organ remains active even while we sleep.

Each neuron is connected to 100,000 others of its kind in a network. When the brain is exhausted, blood flow and electrical activity in this structure decrease. To revive it, however, it’s not enough to eat something or drink coffee. Taking food or stimulants can help, but cell activity is more complex.

For glucose to be used efficiently by cells, several conditions and steps have to be met, so that interruption or malfunction in any of them can interrupt the process and prevent neurons from correctly receiving or transforming fuel.

On the other hand, stress plays a fundamental role in the feeling of brain fatigue, it causes an increase in the levels of cortisol, a hormone that, if present in excess, can influence our ability to concentrate and memory.

Although scientists have yet to fully unravel the brain function and the causes and solutions for mental exhaustion, getting enough rest, eating a proper diet, and avoiding stress and work overload can prevent us from feeling mentally exhausted.

What’s mental fatigue?

Mental fatigue is a concept that can be confused with physical fatigue, although they’re different. Mental fatigue is related to prolonged symptoms of stress (whether or not at work), anxiety, depression, or overwork and lack of resources.

This type of fatigue is different from drowsiness (the need to sleep), although the person feels a loss of energy, lack of motivation and apathy. It appears, for example, when a person suffers burnout and the moment comes when they feel that they cannot take it anymore, that their resources are not enough to face the situation and they reach their mental limit.

That kind of mental exhaustion hits you when the amount of tasks and activities you’ve done exceeds your ability to successfully handle stress (even good stress).

Sometimes mental exhaustion can cause health problems: depression, heart disease, auto-immune disease. It can also lead to insomnia or trouble sleeping which, like a vicious cycle, can cause mental fatigue.

The more mental fatigue you feel, the less you will be able to make decisions, focus, and stay calm.

Physical and mental fatigue

The most widespread belief is that excessive physical exercise leads to muscle fatigue and some injuries, but the brain is also exhausted and fatigued with the abuse of activity. 

Excessive physical training causes the brain to tire losing capacities and this is reflected in making bad decisions.

According to the studies, the people subjected to strong and excessive physical training were affected in the activities of a portion of the brain causing their responses to rewards to be instantaneous, zero consideration and reasoning.

The cognitive work of the brain is affected by physical fatigue, therefore, its control is at risk, it’s important to clarify that the brain gets tired because it also works in the middle of an exercise routine because it is the one who controls the activity, since greater physical effort, greater mental work.

When physical training is exceeded, one of the cerebral cortices is deactivated and the executive control system is affected, so when we are physically exhausted, our mind is also exhausted and decisions are not made with the necessary “coldness”.

There’s a tendency to a quick response because it just wants to rest, the brain wants to disconnect while the body recovers energy.

Physical activity and training are ideal for health, abusing them can have negative reactions in the brain, the neural stats of the brain are upset and the conditions for reasoning are not the most appropriate.

The brain is the command center of the body, that’s why marathon athletes or cyclists, who travel long distances investing a lot of time, say that to resist or achieve success you need a strong mind, it’s not just a matter of strength.

With physical overload, the brain makes impulsive decisions that put many issues in our life at risk and whose impact makes us more vulnerable. 

After physical activity it’s important to rest and when it comes to making decisions, it’s better to be rested, with the body relaxed so that the brain can work better and give us the most appropriate responses.

How to combat mental fatigue

Mental exhaustion, that feeling that you’ve reached the limit and in which you feel mentally and emotionally drained, can be avoided and overcome.

Below you can find natural ways to combat this phenomenon without having to resort to drugs.

1. Good nutrition

Many people experience mental fatigue because they’re not nourished as they should. This can cause a person to lose concentration and feel tired and mentally exhausted, as their body doesn’t have the necessary nutrients to function properly.

2. Sleep

Sleeping well has many benefits, and it is that when we do not, our body and our mind notice it. Therefore, there is nothing better than a good rest to prevent mental fatigue and be more lucid and alert during the day.

Experts recommend 8 hours of sleep, but there are people who need less to perform well. Taking a 20-minute nap a day is not bad either, because according to science it makes us more focused and active.

3. Drink water

If eating well is positive for maintaining good levels of attention and concentration, it is just as necessary to consume enough water. Dehydration is one of the main causes of mental fatigue, so it is necessary to drink at least 8 glasses of water every day, spread out throughout the day.

4. A good work environment

We spend many hours at work and, therefore, a bad work environment can end up causing us an excess of mental fatigue. When you’re comfortable in your work, you feel good and are more productive. When this is not the case, it is easy to feel mentally drained and stressed.

5. Rest

If they are at work and you feel like you can’t take it anymore, mentally speaking, then you may need to take a break and, for example, give your eyes a rest by moving away from the screen. If, for example, you work in front of a computer and you have been in the same position for 3 hours, it’s logical that you feel mentally tired.

Don’t feel guilty and disconnect for 20 minutes, sure that when you return you will feel better. The ideal is to disconnect 10 minutes every 45 minutes.

10. Take a vacation

If you see that your mental fatigue  has turned into exhaustion, then it is time to take a long breath, because you may be suffering from stress or burnout syndrome. It may be a good idea to take a weekend vacation in the mountains or spend the day in the countryside or on the beach. The goal is to relax, let your mind rest, and recharge.

Our brain, like our body, gets tired.

FAQs: Does the brain get tired?

Can your brain feel tired?

Yes, your brain can feel tired.
This is expressed in mental fatigue. This is caused by many hours of cognitive activity.

What happens when the brain is tired?

When your brain is tired it causes interruptions in cellular communication, making it difficult for you to concentrate and make decisions.

How do you overcome brain fatigue?

Rest your mind
Reduce excess activities
Eat well
Prioritize your activities

Why does my brain feel tired after studying?

The more you study, the more your brain activity uses up glucose. This reduction in glucose makes you feel exhausted.

What time of day is your brain sharpest?

Between 10:00 and 2:00 pm is the ideal time to perform tasks that require greater concentration.

In this article answered the question ‘’Does the brain get tired?’’ We discussed the relationship between physical and mental fatigue and why we tend to feel tired after work hours.

If you have any comment or question please let us know!


Marcora, S. M., Staiano, W., & Manning, V. (2009). Mental fatigue impairs physical performance in humans. Journal of applied physiology, 106(3), 857-864.

Secher, N. H., Quistorff, B., & Dalsgaard, M. K. (2006). The muscles work, but the brain gets tired. Ugeskrift for laeger, 168(51), 4503-4506.