An article on BBC Online just yesterday told about the surprising (to the scientists!) discovery that the brain, like the rest of the body, becomes depleted of glucose and, under hard functioning (like heavy study, difficult mental tasks, etc.) needs replenishing. Apparently it was thought previously that the brain always had plenty of glucose.
What a surprise to find out that the brain is part of the body!
Don't you just love some of these studies?
Anyway, this makes yet another case for snacking as contrasted to widely spaced meals.