T,
The human brain requires two things to function properly and to regain alertness. Salt and water. These two things cause the brain's electrical charges to fire, thus refreshing (this is all layman's terms) the brain's ability to think clearly. For those sluggish times of day, drink lots of extra water, eat nuts, salted almonds are best. The protein, salt and water will keep you going! Candy and sweets, fruit is fine, will give you a momentary jump start, then leave your more sluggish than if you ate nothing. Okay, now that I've bored you with a science lesson, back to work!