Scientific research has found no link between eating sugar and hyperactivity. However, research does show that sugar influences behavior and can cause a reduced attention span. One theory is that the decrease in attention span is behind the belief that sugar makes people hyper.
The idea that sugar causes hyperactivity is linked to a study by Dr. Benjamin Feingold in 1973. The study advocated the removal of additives in children's food because these additives were believed to make children more hyperactive. It included additives such as artificial flavors and dyes. The study never specifically mentioned the removal of sugar, but sugar was lumped together in the category of additives.
Studies at Yale did, however, find a link between sugar and its ability to influence behavior. One such study showed a link between children having large amounts of sugar for breakfast and suffering from a lower attention span compared to children who ate whole grains for breakfast. Another study from Yale showed a link between children who ate sugar and had higher adrenaline levels. It was concluded that this was likely because sugar is absorbed into the bloodstream quickly, which increases blood sugar levels. The symptoms of high adrenaline levels are very similar to those of hyperactivity.