According to research published in the journal Current Biology, intense and prolonged cognitive work can indeed make you tired, even though you’re just sitting down!
That’s right – it’s now been explained why thinking hard for hours at a time can wear you out!
Apparently, it can cause potentially toxic byproducts to build up in the prefrontal cortex so your mental exhaustion is not just in your head!
This buildup can then alter your control over decisions, leading to a shift toward actions requiring no effort as cognitive fatigue sets in.
Researcher Mathias Pessiglione from the Pitié-Salpêtrière University in Paris, France, explains that “Influential theories suggested fatigue is a sort of illusion just cooked up by our brains to make us stop whatever we are doing and to turn to a more gratifying activity. But our findings show that cognitive work does result in a true functional alteration—accumulation of noxious substances—so fatigue would be a signal that makes us stop working but for a whole different purpose: to preserve the integrity of our brains functioning.”
Pessiglione, first author Antonius Wiehler and their colleagues started this research because they wished to truly understand mental fatigue and why it happens.
They started by hypothesizing that there is a need to recycle potentially toxic substances caused by neural activity and to prove this theory, they used magnetic resonance spectroscopy in order to monitor brain chemistry during a full workday.
As part of this study, they had 2 groups of people – one having to do rather simple cognitive tasks and another that was required to really use their brains.
And sure enough, recognizable signs of fatigue appeared only in the group doing hard cognitive work.
Furthermore, they also presented high levels of glutamate in synapses of the brain’s prefrontal cortex when compared to the other group.
Basically, their theory was proven right! But is there a way to overcome our brains’ limitations when it comes to thinking hard so we can maximize our mental potential?
Pessiglione stresses that “Not really, I’m afraid. I would employ these good old recipes: rest and sleep! There’s good evidence that glutamate is eliminated from synapses during our sleep.”