The newest study finds that eating milk chocolate may boost brain function. It contains many substances that act as stimulants, such as theobromine, phenethylamine, and caffeine.

These substances by themselves have previously been found to increase alertness and attention and what we have found is that by consuming chocolate you can get the stimulating effects, which then lead to increased mental performance.

There was a study about the effects of various chocolate types on brain power, the group of volunteers had to consume, on four separate occasions, 85 grams of milk chocolate; 85 grams of dark chocolate; 85 grams of carob; and nothing (the control condition).
After a 15-minute digestive period, participants completed a variety of computer-based neuropsychological tests designed to assess cognitive performance including memory, attention span, reaction time, and problem solving.

Composite scores for verbal and visual memory were significantly higher for milk chocolate than the other conditions.
Previous research has shown that some nutrients in food aid in glucose release and increased blood flow, which may augment cognitive performance. The current findings, said Raudenbush, "provide support for nutrient release via chocolate consumption to enhance cognitive performance."