Despite evidence to the contrary many parents still believe that sugar causes hyperactivity in their kids so they won't give them candy. While this has been proved an old wives tale, many parents will nonetheless swear to the fact that their kids go bonkers on sugar. There are two probabilities for this happening.
The first is that if a persons glucose levels are low, the ingestion of glucose into the body will feel like a sugar rush resulting in an increased burst of energy. This is similar to the replenishment of many other nutrients that the body requires. For example, an anaemic person (a person with low iron) will feel lethargic and when a couple of iron tablets are taken they will feel a rush of energy very quickly. This will only occur if iron levels are low and the same is true for glucose. A sugar rush will only be experienced by a person low in glucose which is necessary for proper body function.
The second possibility is that parents and children expect sugar to translate into hyperactivity and so it does – the placebo effect. This is not to say that a person is faking, not at all. The power of the mind over the body is a well known fact. If the mind believes something to be true it can easily create a physical response in line with that belief. This is never more evident than when a child is hurt or sad and a parent offers candy consolation. We've all seen a child go from severe distress to smiles when a candy or chocolate is offered. This isn't the child faking it, nor was the child's suffering unreal. The placebo effect of candy and chocolate for young children is so strong that the minds link between candy and pleasure takes over from the very real pain the child is feeling.
Although the evidence suggests that sugar itself doesn't hype kids up, parents aren't imagining things. Between low glucose levels and a placebo effect children exhibit an evident response to the candy. The twist is that what the candy is doing is actually improving the glucose and psychological condition of the child's body.