Fatigue: It is the formation of clouds in the brain that can lead to memory loss. It is accompanied by drowsiness and lack of energy. Clinically it is the lack of phosphorus. Good nutrition. To avoid mental fatigue it is necessary to keep the supply of energy in your body constant since your brain requires nutrients, as well as your muscles. To do this, do not hold long periods of fasting. In times of high tension, eat those that are easy to digest such as pasta, legumes, cereals and dairy.