Why Is Milk White?: & 200 Other Curious Chemistry Questions (2013)

Why does sugar make you hyper?

It doesn’t. The myth of sugar-induced hyperactivity has been disproven many times. But people continue to believe it, because situations that cause children to get excited, such as parties and holidays, are also situations where a lot of sugar is present. But in fact, the sugar may cause the most excitement before it is eaten, rather than afterward.

The parents of the children have been taught to expect hyperactivity due to sugar, and so when they see hyperactivity and sugar together, they infer a cause and effect. But when there is hyperactivity and no sugar present, they don’t wonder that excitement can happen in the absence of sugar. This is similar to an effect called the full moon effect, named because nurses were once convinced that hospitals are busier during a full moon, despite records proving otherwise. The nurses would see a busy hospital and a full moon and associate the two. But when the hospital was busy when there was no full moon, they did not think to associate the lack of a full moon with the busy hospital.