It’s true that your brain stops working! Thinking can also make you tired!

After finishing a day's work, modern workers just want to lie down on the bed when they get home and do nothing. Although they don't do physical labor, thinking every day can make people feel exhausted and feel that their brains are not working anymore. So, will long-term brain fatigue affect people's physical health?

Source: Internet

Research on cognitive fatigue (fatigue caused by excessive use of the brain) has been going on for more than a century, but the causes behind it are still not fully understood. A recent study published in Current Biology provides new evidence that it turns out that mental work is much more tiring than it seems to be.

Source: sciencedirect.com

1

Observation of cognitive fatigue

Researchers from the Pitié-Salpêtrière Hospital and the Paris Brain Institute in Paris recruited 40 participants and divided them into two groups: a difficult group of 24 people completed a difficult computer-based task, and an easy group of 16 people performed an easy task. For 6.25 hours, all participants were asked to perform two cognitive control tasks (switch and return) that induced cognitive fatigue.

Letters were displayed on a computer screen every 1.6 seconds. In the switch task, participants had to distinguish vowels from consonants or uppercase from lowercase based on the color of the letters, with the difficulty depending on the color change. In the return task, participants had to indicate whether the letter on the screen was the same as the letter presented N trials before, with the difficulty of the task related to the interval between two trials (i.e., the amount of information to be retained in memory).

Source: "A neuro-metabolic account of why daylong cognitive work alters the control of economic decisions"

The researchers also asked the participants to make four economic decisions after the experiment, such as choosing to receive 41.20 euros immediately or 50 euros a month later. The result was that the participants in the difficult group were more likely to make impulsive choices than those in the simple group (about 10% more) , and over time, in economic decisions, the difficult group began to choose options that required less thinking and calculation. This shows that cognitive fatigue affects the work state and mood of the participants in the difficult group.

2

Glutamate: the driving force behind the scenes

So, what differences were occurring in the brains of the two groups of participants?

The researchers used magnetic resonance spectroscopy (MRS) to examine metabolites in the participants’ neural tissue and found that participants in the difficult group had higher levels of glutamate accumulated in the lateral prefrontal cortex (LPFC) of their brains (up about 8%).

(A) MRS data collection of neurometabolites (B) MRS results of glutamate levels

Source: "A neuro-metabolic account of why daylong cognitive work alters the control of economic decisions"

The LPFC is the brain's command and control center, where higher-level thinking, such as decision-making and self-control, takes place. Glutamate is the most abundant neurotransmitter in the central nervous system and is an excitatory neurotransmitter that must be tightly balanced with inhibitory neurotransmission for the brain to function properly.

Glutamate

Source: Wikipedia

At the same time, glutamate is a "two-faced person". For the intracellular compartment, it is a useful resource that can combine with ammonia in the blood to form glutamine, thus having a "detoxification" function. In the extracellular compartment, glutamate becomes a toxic byproduct, so it is important to limit the release of glutamate.

When a large amount of glutamate accumulates in the extracellular compartment, the excitation/inhibition balance of nerve cells will be destroyed, and the synaptic transmission signals between neurons will be disturbed. This will trigger a regulatory mechanism that increases the cost of LPFC activation and causes a decrease in the brain's cognitive control ability. This also explains why cognitive control is more difficult to mobilize and people become very tired after a day of high-intensity work.

The transmission of excitement between neurons

Source: pixabay

It is generally believed that cognitive fatigue is a feeling produced by the brain to let you rest. However, this study shows that its real purpose is to protect the brain's function from being damaged.

Source: pixabay

So, is there any way to eliminate the limitations of thinking fatigue? The answer is: the best way at present is to rest and sleep, because the concentration of glutamate will decrease during sleep, making the brain's fatigue gradually disappear.

There are still many questions to be studied in the future, such as: How does the brain monitor glutamate levels? Why is glutamate more easily accumulated in cognitive control areas than in other areas such as the visual cortex? How do glutamate levels recover during rest or sleep?

3

How to relieve fatigue?

After a tiring day, when you get home and have dinner, do you like to relax by lying on the sofa and browsing your phone or playing games? But doing so does not really relax the brain, because the brain still needs to process information, and looking at electronic screens for a long time can also damage your eyesight. So, what are the correct ways to relax?

1. Ensure adequate rest time

Put down your phone, listen to soothing music before going to bed, practice meditation, or massage your head to relax your brain. Try to go to bed early and get enough sleep, preferably entering deep sleep around 11pm. If you lack sleep for a long time or suffer from insomnia, your brain will become slow to respond to the outside world and your thinking will become inactive, which will affect your study and work.

Source: pixabay

2. Use your brain moderately

Pay attention to the combination of work and rest, and relax in moderation. During work, you can let your brain rest for about 10 minutes every hour, such as looking into the distance or listening to a song. Excessive use of the brain may disrupt the balance of inhibition/excitation of the cerebral cortex, causing neurological disorders, reduced memory and judgment, and causing serious damage to the brain.

Source: unsplash

3. Get proper physical exercise

It is certainly comfortable to "lie down" at home on weekends, but lying down for too long is not good for the body and will increase the risk of other diseases. Therefore, it is necessary to maintain a certain amount of exercise. Exercise can speed up the blood circulation of the human body, promote metabolism, and help the brain absorb nutrients. If your motor cells are not well developed, you can choose a more soothing exercise method, such as walking, short-distance jogging, Tai Chi, etc.

Source: pixabay

4. Create a comfortable environment

Studies have shown that in a relatively quiet working environment with smooth air flow, suitable temperature and humidity, the brain is more capable of processing information and is more likely to eliminate fatigue. Therefore, attention should be paid to ventilation in the office, reducing noise and creating a more soothing environment.

Mental work may seem like the body is "idle", but in fact the brain is often in a very "busy" state. If one day the potential of the brain is fully developed, will it be liberated? Let's wait and see, but before that, please treat your brain well.