“Brain cells consume oxygen and glucose (a form of sugar) for fuel. The more challenging the brain’s task, the more fuel it consumes. Therefore, it is important to have adequate amounts of these substances in the brain for optimum functioning. Low amounts of oxygen and glucose in the blood can produce lethargy and sleepiness. Eating a moderate portion of food containing glucose (fruits are an excellent source) can boost the performance and accuracy of working memory, attention and motor function.

Water, also essential for healthy brain activity, is required to move neuron signals through the brain. Low concentrations of water diminish the rate and efficiency of these signals. Moreover, water keeps the lungs sufficiently moist to allow for the efficient transfer of oxygen into the bloodstream…

Many [people] do not eat a breakfast that contains sufficient glucose, nor do they drink enough water during the day to maintain healthy brain function…The current recommended amount is one eight-ounce glass of water a day for each 25 pounds of body weight.” -From, “How The Brain Learns” By: David A. Sousa