No doubt, physical labour wears you out. But what about mental stress or labour? Will , but what about hard mental labor? If you sit and think hard for hours, then sure you are going to feel worn out. Researchers have now come up with evidence to explain and the reason why one feel mentally exhausted.
In the study the researchers found that intense cognitive work prolonged for several hours causes potentially toxic byproducts to build up in the part of the brain known as the prefrontal cortex. This in turn alters control over decisions. This gives a shifts toward low-cost actions requiring no effort or waiting as cognitive fatigue sets in, the researchers explain.
Researcher Mathias Pessiglione of Pitié-Salpêtrière University in Paris, France, noted that cognitive work results in a true functional alteration—accumulation of noxious substances—so fatigue would indeed be a signal that makes us stop working but for a different purpose: to preserve the integrity of brain functioning.
MENTAL LABOUR; METHOD
The researchers used magnetic resonance spectroscopy (MRS) to monitor brain chemistry over the course of a workday. They looked at two groups of people. One group who needed to think hard and the other who had relatively easier cognitive tasks. In the study, the researchers found signs of fatigue, including reduced pupil dilation, only in the group doing hard work. Those in that group also showed in their choices a shift toward options proposing rewards at short delay with little effort. Critically, they also had higher levels of glutamate in synapses of the brain’s prefrontal cortex. Together with earlier evidence, the authors say it supports the notion that glutamate accumulation makes further activation of the prefrontal cortex more costly, such that cognitive control is more difficult after a mentally tough workday, the researchers noted.