Experts discover surprising daily activity that’s making you ‘tired all the time’

Have you ever felt exhausted despite not working hard physically?

Whether it’s thinking about what to eat, what to wear or remembering to charge your phone, modern life is filled with decisions from the moment we wake up.

While these simple choices may not feel like strenuous tasks, studies suggest they can overload our brains and leave us feeling tired all the time.

At the end of a day of seemingly minor cognitive tasks, it can be even harder to make rational decisions, and experts say a build-up of a specific chemical in the brain may be to blame.

Here, MailOnline reveals why decision fatigue is really leaving us all exhausted.

When we make a decision, the brain sends an electrical signal between brain areas along wire-like structures called neurons.

But to send these messages it needs a chemical in the brain called glutamate, a neurotransmitter.

Researchers have found that after making a decision, this chemical glutamate lingers, builds up and essentially clogs the brain, with the effect getting worse after more and more decisions.

The discovery, from experts at the Paris Brain Institute in France, came after they measured the levels of these brain chemicals in the organ and the effect they had on the performance of challenging tasks.

They focused on a part of the brain called the lateral prefrontal cortex – a part of the brain that tackles difficult tasks and makes decisions.

The 2022 study saw 40 people perform memory tasks for six hours while lying in an MRI scanner.

One task involved looking at series of numbers appearing on a screen and judging whether the current number was the same as the previous one. An easier task was given to 14 people, while a more difficult task was given to 26 people.

Glutamate was measured along with eight different brain chemicals at different points during the cognitive exercises.

But curiously, at the end of the challenges, both groups had the same levels of glutamate in their lateral prefrontal cortex compared to the start of the experiment.

This suggests that it is the volume of tasks that causes this mental build-up, rather than their difficulty.

But researchers noted that people who performed the more difficult tasks showed other signs of fatigue, such as dilation of the pupils in their eyes, which was not the case for the group that did the easier task.

The study also looked at how this mental fatigue affects how well people make decisions.

In between the memory tasks, researchers gave the participants other exercises, for example where people could choose between a smaller amount of money immediately or a larger amount of money later.

As people doing the more difficult memory tasks became more tired, they began to accept a small reward that would be given to them immediately, but in the other group this was not always the case.

This suggested that they chose the option that required the least decision making.

Experts from the Paris Brain Institute in France noted that sleep could help rebalance glutamate levels in the brain, but stressed that more research is needed.

Other studies have also highlighted that decision fatigue actually affects our ability to think clearly.

One 2016 studypublished in Chronobiology International, revealed that people make more rational decisions earlier in the day.

Participants were asked to play a game where they had to accept or reject various economic offers from a virtual participant. They completed this match at both 9am and 5pm.

Researchers found that more cautious decisions were made in the morning, while participants spent less time responding to high-uncertainty offers in the evening.

Another 2021 studypublished in the Journal of Retailing and Consumer Services, surveyed more than 1,000 participants about impulse buying and also found that people were more likely to make impulsive decisions later in the day.

These both suggest that we make bad decisions later in the day when our brains are tired.

But there are suggestions that a short rest can help recharge the brain.

According to a 2021 study published in the National Bureau of Economic Research, which looked at decisions made by Major League Baseball umpires, found that they had a depleted “budget” of attention.

But after short breaks during a game, they were able to replenish these attention budgets.

Authors of the study say this could be replicated in other work environments and suggested that having short breaks during the working day could help people in ‘cognitively demanding jobs’.