That’s only sort of correct. It’s only true if you narrowly define hyperactivity as some very specific condition. The studies clearly say that people can experience a “sugar rush” after consuming sugar. The problem is that “sugar rush” is exactly what most people mean when they say hyperactivity. Hyperactivity as in activity that becomes hyper. Hyper as in “above or excessive”, activity as in “doing stuff”. So, “doing excessive stuff”.