If you’ve ever felt drained after doing a crossword puzzle, working a math problem or taking a test, there’s a reason, says Dr. Paul Foster, professor of clinical psychology at Middle Tennessee State University and a practicing psychologist.
“There is an idea out there that you have a process of cognitive fatigue that is similar to physical fatigue. If you’re exercising, you get tired. If you’re using your brain, it feels tired,” Foster said.
The fatigue occurs likely because of a physiological process.
“Whenever you learn information, you’re developing connections between populations of neurons in the brain. … If you learn something, then something has changed in your brain,” Foster said. “The neuron structure is changing.”
The process is called long-term potentiation, which is a long-lasting enhancement in signal transmission between neurons. Essentially, your brain becomes stronger.