A new study has found that mental fatigue may be caused by toxic byproducts that build up in the brain.
The study, which was published in Current Biology earlier this week, looked at the brain activity of two groups of people: those who needed to think hard and those who had relatively easier cognitive tasks. The study found that the group who had to think harder showed signs of mental fatigue.
This included reduced pupil dilation, a shift toward tasks that offered quick rewards with little effort and higher levels of glutamate in synapses of the brain's prefrontal cortex. The potentially toxic byproducts build up to force people to take a break or focus on something else, the researchers theorised.
