Dr. Wesnes conducted a study in which he found that having a large amount of sugar for breakfast led to a severe deterioration of attention span when compared to having no breakfast or eating whole grain cereal. Dr. Tamborlane, also from Yale, reported that children given sugar had higher levels of adrenaline. A possible explanation for this effect is that since sugar is quickly absorbed into the bloodstream, blood sugar rises quickly, which can lead to higher adrenaline levels and thus symptoms similar to those associated with hyperactivity. Furthermore, children with ADHD also tend to have higher levels of insulin.