A long, hard day of thinking can sometimes feel as exhausting as a day of manual labor, and experts think they know why.
A new study has found that people can feel fatigued after intense mental work because it causes potentially toxic byproducts to build up in the prefrontal cortex part of the brain.
It alters a person’s control over decisions, so that they turn to actions that require no effort or expectation when mental fatigue sets in.
Fatigue is a way of telling the brain to stop to save itself.
Mathias Pessiglione from the University of Pitié-Salpêtrière in France, said: “Influential theories suggest that fatigue is a kind of illusion concocted by the brain to make us stop whatever we are doing and turn to an activity. more rewarding.
“But our findings show that cognitive work translates into real functional impairment – accumulation of harmful substances – so fatigue would be a signal that makes us stop working but for a different purpose: to preserve the integrity of brain function.”
The scientists monitored brain chemistry during a working day in two groups of people – those who needed to think hard and those who had relatively easier cognitive tasks.
In the first group, they observed signs of fatigue, including reduced pupil dilation, and people in this group made choices toward options that offered short-term reward with little effort.
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The researchers added that this group had higher levels of a chemical called glutamate in the prefrontal cortex.
They say this supports the theory that glutamate buildup makes extra activation of this part of the brain costly, so much so that cognitive control is more difficult after a mentally demanding day at work.
The results were published in the journal Current Biology.
A long, hard day of thinking can sometimes feel as exhausting as a day of manual labor, and experts think they know why.
A new study has found that people can feel fatigued after intense mental work because it causes potentially toxic byproducts to build up in the prefrontal cortex part of the brain.
It alters a person’s control over decisions, so that they turn to actions that require no effort or expectation when mental fatigue sets in.
Fatigue is a way of telling the brain to stop to save itself.
Mathias Pessiglione from the University of Pitié-Salpêtrière in France, said: “Influential theories suggest that fatigue is a kind of illusion concocted by the brain to make us stop whatever we are doing and turn to an activity. more rewarding.
“But our findings show that cognitive work translates into real functional impairment – accumulation of harmful substances – so fatigue would be a signal that makes us stop working but for a different purpose: to preserve the integrity of brain function.”
The scientists monitored brain chemistry during a working day in two groups of people – those who needed to think hard and those who had relatively easier cognitive tasks.
In the first group, they observed signs of fatigue, including reduced pupil dilation, and people in this group made choices toward options that offered short-term reward with little effort.
Read more from Sky News:
Fatigue responsible for a quarter of fatal road accidents
The researchers added that this group had higher levels of a chemical called glutamate in the prefrontal cortex.
They say this supports the theory that glutamate buildup makes extra activation of this part of the brain costly, so much so that cognitive control is more difficult after a mentally demanding day at work.
The results were published in the journal Current Biology.