“Our findings show that cognitive work leads to real functional changes.” (Image: Getty)

Research has found evidence to suggest that feeling emotionally drained isn’t just in your head, so to speak.

Mental fatigue can be just as exhausting as physical work.

According to the study, published in Current Biology, after hours of intense mental work, potentially toxic byproducts accumulate in a part of the brain called the prefrontal cortex.

This affects our control over the decisions we make. In other words, it means switching to activities that consume less mental energy.

Essentially, the brain distracts us from doing more work to save ourselves.

In this study, researchers recruited two groups of people to monitor their brain chemistry at work.

One group had to think throughout the day and the other group had to think of relatively simple tasks.

In the group that did the hardest work, the researchers saw signs of fatigue, including reduced pupillary dilation.

Woman thinking at office desk

It’s not just in your head, so to speak (Image: Getty Images/Westend61)

We also found that participants chose tasks that offered rewards with little delay or effort.

The team also found higher levels of a chemical called glutamate in the brain’s prefrontal cortex in this more intense thinking group.

In addition to the above findings, the study authors said their results suggest that the buildup of glutamate makes it more difficult to activate this part of the brain further, and cognitive control declines after a day of mentally demanding work. Even harder.

“The prevailing theory is that fatigue is an illusion designed by the brain to force us to stop what we’re doing and move on to a more pleasurable activity,” said Matthias Pesiglione of France’s Pitiers-Salpetriere University.

“However, our findings show that cognitive work leads to actual functional changes: accumulation of toxic substances. So while fatigue is certainly a signal for us to stop working, it has another purpose: to maintain the functional integrity of the brain.”

So what can we do about it?

The paper notes that glutamate levels drop during sleep, making it more important than ever to get a good supply of z.

We recently spoke to MBST UK founder and director Elizabeth Clare about her 7 simple steps to improve your sleep and well-being.

This included improving food quality, reducing alcohol consumption, and reconfiguring rooms.

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