Exhaustion at work: Why do we think so tired

Do you know the feeling of being completely drained after work and falling exhausted on the sofa – even though you really crouched on your office chair all day? While it is often considered normal in physical work when you are tired in the evening, many office jobbers are sometimes surprised at the evening deep.

But yes – thinking also makes us tired at some point. A study published in the journal “Current Biology” shows what mental work costs us.

The French research team led by Antonius Wiehler from the Paris Brain Institute had 40 participants solve various tasks on the screen. Sometimes they had to sort letters by colors, sometimes by vowel and consonant. The setting also included memory exercises.

The researchers did not allow their subjects to complete hundreds, but thousands of these tests in two different levels of difficulty in order to achieve fatigue.

“After six hours, regardless of the difficult of the task, both groups stated that they feel exhausted,” said Antonius Wiehler, first author of the study and behavioral researcher at the Paris Brain Institute at the presentation of the study, but that could also be due to the fact that we were conditioned to feel exhausted after a working day.

Now the Paris research team is not the first group to take care of the phenomenon of thinking. A few years ago, scientists, for example, were able to find out that the lateral prefrontal cortex plays a major role in intensive thinking and important decisions.

So far, however, little has been researched why the whole thing sometimes leads to exhaustion and concentration disorders.

So the Paris scientists took a look at a special magnetic resonance spectroscopy, which happens in the brain in spiritual work. The result: Glutamat makes thinking difficult. “In the groups that had to solve the more difficult tasks, the glutamate concentration rose significantly more over time,” explains Wiehler.

The amino acid glutamate is one of the most important messenger substances in the brain and can not only cause concentration disorders, but also headache and racing heart. In high concentrations, however, glutamate looks toxic. Reason enough for our body to actively regulate the glutamatal balance. However, if we do intensive intellectual work, the compensation is obviously difficult.

And what if the glutamate gets out of hand? The research team has a guess: If the front cerebral cortex produces too much glutamate, it becomes more difficult to activate nerve cells. Actually, the area in the brain is responsible for regulating feelings, planning actions and maintaining self -control. A glutamate surplus therefore leads to exhaustion and lack of self-control.

Antonius Wiehler also presented what this means for our everyday life with the study: He presented the test subjects with the choice: “Would you like 20 euros or 50 euros in one year?” The participants, who had to solve the cognitively difficult tasks, tend to decide on the quick money, while the other group thought long -term.

Wiehler’s conclusion: “If the cognitive fatigue begins, we opt for simpler processes or actions that, for example, do not require any effort or waiting.”

Overall, the study shows that Glutamat plays a role in cognitive exhaustion. Fritjof Helmchen from the Institute for Brain Research at the University of Zurich said in an interview with “Spectrum”: “It is not clear whether an increased glutamate content leads to dwindling nerve activity in the front cerebral cortex. However, the study shows that both are related.”

However, a small increase in the glutamate mirror with a targeted suggestion is nothing new for the neurophysicist Harald Möller from the Max Planck Institute. In conversation with the German Press Agency, he points out that the messenger fabric quickly dropped again after the end of the stimulation. That is why, in his view, the French researchers should have measured the glutamal share during rest phases in order to have a holistic picture.

Either way – Glutamat plays a role if we want to go straight to the sofa from the office chair. And according to the Paris scientists, it is also what brings our glutamatal budget into balance: a large portion of sleep.

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