Using your brain all day literally wears you out — and makes it harder to make bigger decisions, according to a new study.
Cognitive fatigue “has been conceived as an inflated price of cognitive control, objectified by more impulsive decisions,” the study wrote, aka the loss of the ability to control your thought processes just as easily and make more spontaneous decisions.
Scientists had several explanations for why people experience cognitive fatigue, according to the study, published last week in the Current Biology log.
One explanation is that the brain does it on purpose, “to make us stop what we are doing and move on to a more satisfying activity,” Mathias Pessiglione of Pitié-Salpêtrière University in Paris, France, said. in a press release.
It’s not an illusion generated by the brain, this study states.
“Our findings show that cognitive work results in a real functional change – accumulation of harmful substances – so fatigue would indeed be a signal that causes us to stop working, but with a different goal: to maintain the integrity of brain functioning” Pessiglione said in the statement.
Why is it harder to make decisions after a long day?
The study found that after several hours of performing difficult tasks, people had more glutamate in the lateral prefrontal cortex, which is responsible for assessing and solving problems.
Having glutamate in the right amounts at the optimal times is associated with better brain function, but too much has been linked to brain diseases, according to Cleveland Clinic.
When the chemical builds up — perhaps like emails at the end of a long day — it’s harder for your brain to work, according to the release.
“While machines can calculate continuously, the brain cannot,” the release added.
There were a few other indicators of cognitive fatigue. In the study, the group who performed difficult tasks throughout the day tended to make “cheaper” decisions later, such as choosing immediate, shorter-term rewards over more difficult but lucrative decisions.
The trick, according to the release, is to not even ask yourself how tired you are — the results of the subjective reporting measure showed a discrepancy between how tired people felt and other cognitive function measures — but to lean on an old-fashioned remedy: rest.
“I would use good old recipes: rest and sleep! There is good evidence that glutamate is eliminated from synapses during sleep,” Pessiglione said in the release.
An other way? Do something you enjoy. Phillip Ackerman, a psychology professor at the Georgia Institute of Technology who was not involved in the study, told CNN that you are less likely to become cognitively fatigued by an activity you enjoy than by an activity you don’t.
