Mental effort refers to the cognitive resources required to perform tasks that demand attention, concentration, and problem-solving. It involves the brain's ability to process information, make decisions, and manage distractions. Activities like studying, working on complex problems, or learning new skills often require significant mental effort. This effort can lead to mental fatigue, which is the feeling of tiredness or reduced performance after prolonged cognitive activity. Factors such as stress, lack of sleep, and multitasking can increase mental effort and contribute to fatigue. Understanding mental effort is essential for improving productivity and maintaining overall cognitive health.