Sugar seems like the obvious culprit when kids get overexcited after eating cake, ice cream and who knows how much Halloween candy.
But ask an expert in how the body metabolizes sugar, and she'll tell you there's no reason candy should cause a high compared to other sugars.
"It's a myth," said Elizabeth Rosolowsky, a pediatric endocrinologist in the University of Alberta's Faculty of Medicine & Dentistry.
"Parents may observe more energy in their kids after eating sugar, but it's one of those self-fulfilling notions—a belief that comes true because we are acting like it's true," she said.
More often than not, the child is riding the energy of the activities that lead to consuming sugar, such as a family outing for ice cream, a birthday party or embarking on a dress-up hunt to collect as much candy as possible, said Rosolowsky.
"A well-regulated mechanism works in healthy bodies to keep blood sugar levels in a tight range, regardless of whether you are bingeing on sugar or have gone 24 hours without eating," she explained.
"I've seen actual sugar highs, or hyperglycemia, in people who have Type 1 diabetes, and while they do experience changes in behaviour, it's the opposite of ebullient. They get headaches, can't concentrate and don't feel well.
A little sugar is not bad for us
"In fact, our bodies need some sugar to survive," said Rosolowsky.
The body breaks down carbohydrates into single, simple sugar molecules like glucose, which are the body's first energy source. Insulin, produced by the pancreas, helps transport glucose into our cells.
"In physiologically healthy people, the pancreas is making enough insulin no matter how much you eat, in order to maintain blood glucose levels in a tight range and ensure we don't experience sugar highs or lows," she explained.
We run into problems with sugar when our bodies can no longer make insulin to use the glucose or our bodies don't use the insulin well or are insulin resistant, said Rosolowsky.
"Eating sugar itself does not cause diabetes. Extra sugar in excess of what a body needs gets stored as energy reserves, like fat, and over time, this can predispose to other conditions like heart disease and obesity."
Bottom line, come Halloween, sugar highs are as likely as ghosts, and moderation is key.
"How a child eats and his or her eating habits are not made or broken in one night," said Rosolowsky.
Instead, parents who set regular expectations about moderation and healthy eating can rest easy if their kids enjoy more candy than usual over Halloween, she added.
Explore further: Halloween doesn't have to be a horror for children's teeth