Have you ever felt exhausted even though you haven’t physically worked hard?
Whether it’s thinking about what to eat, what to wear, or remembering to charge your phone, from the moment we wake up, modern life is full of decisions.
Although these simple choices may not seem like strenuous tasks, studies suggest they could overload our brains and make us feel tired all the time.
In fact, at the end of a day full of seemingly minor cognitive tasks, we may find it even harder to make rational decisions, and experts say the buildup of a specific brain chemical could be to blame.
Here, MailOnline reveals why decision fatigue is really wearing us all down.
Although simple choices may not seem like a difficult task, they could overload our brain and make us feel tired all the time.
Researchers have discovered that after you’ve made a decision, this chemical glutamate simply sticks around, builds up, and clogs up the brain.
When we make a decision, the brain sends an electrical signal between regions of the brain along cable-like structures called neurons.
But to send these messages you need a brain chemical called glutamate, a neurotransmitter.
Researchers have found that after a decision is made, this chemical glutamate remains, building up and essentially clogging the brain, and the effect gets worse and worse after more and more decisions.
The discovery, made by experts at the Paris Brain Institute (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.
2022 study He watched 40 people perform memory tasks for six hours while lying in an MRI scanner.
One task involved observing sequences of numbers appearing on a screen and judging whether the current number was the same as the previous one. 14 people were given an easier task, while 26 were given a more difficult one.
Glutamate along with eight different brain chemicals were measured at various points during the cognitive exercises.
But interestingly, at the end of the challenges both groups had the same levels of glutamate in their lateral prefrontal cortex compared to the beginning of the experiment.
This suggests that it is the number of tasks that causes this mental backlog, not their difficulty.
The researchers found that those who participated in the more difficult tasks had higher levels of glutamate in the lateral prefrontal cortex compared to the beginning of the experiment.
But the researchers noticed that people who performed the more difficult tasks showed other signs of fatigue, such as dilated pupils in their eyes, which was not the case in the group who performed the easier task.
The study also looked at how this mental fatigue affects the way people make decisions.
Between the memory tasks, the researchers gave the participants other exercises, such as one in which people chose between receiving a smaller sum of money immediately or a larger one later.
When people performing the more difficult memory tasks became more tired, they began to accept a small reward that they would get immediately, but this was not always the case with the other group.
This suggested that they were choosing the option that required the least amount of decision making.
Experts at the Paris Brain Institute in France said 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.
Experts from the Paris Brain Institute (France) noted in the study that sleep could help rebalance glutamate levels in the brain, but they emphasize that more research is needed.
one 2016 studypublished in Chronobiology International revealed that people make more rational decisions earlier in the day.
Participants were asked to play a game in which they had to accept or reject different financial offers proposed by a virtual participant. They completed this game at 9 a.m. and 5 p.m.
The researchers observed more cautious decision-making in the morning, while in the evening participants spent less time responding to high-uncertainty offers.
Another 2021 studypublished in the Journal of Retailing and Consumer Services, surveyed more than 1,000 participants about impulsive buying and also found that people were more likely to make impulsive decisions later in the day.
Both suggest that we make poor decisions later in the day, when our brains are tired.
But there are suggestions that a short break can help recharge the brain.
According to a 2021 study published in the National Bureau of Economic Research, which analyzed decisions made by Major League Baseball umpires, found that they had an exhaustible attention “budget.”
But after brief breaks during a match they managed to replenish these attention budgets.
The study’s authors said this could be replicated in other work settings and suggested that having short breaks during the workday could help people in “cognitively demanding jobs.”