Contrary to popular belief, sugar doesn't make kids hyper. The science is beyond settled on this issue.
The only types of studies that truly "settle" science are randomized controlled trials. Considered the gold standard in research, they do the best job of controlling for factors that could bias study results.
No fewer than twelve of these studies have been conducted to figure out whether sugar causes hyperactivity. "That's probably more randomized controlled trials than most drugs go through," says Aaron Carroll, director of the Center for Health Policy and Professionalism Research at Indiana University School of Medicine and blogger at The Incidental Economist.
And in every case the trials show that sugar simply doesn't cause hyperactivity.
He lays out the evidence in this video:
In one study that Carroll highlights, a group of kids were all given something to drink, and parents were asked to rate their children's behavior. Parents who were told that their children were given a sugary drink were significantly more likely to report that their children were acting hyper than parents who were told their kid had been given something sugar-free to sip on.
The twist? The researchers had lied to the parents — every single child actually received a drink that was sugar-free.
"It is not the sugar, parents just believe it is," Carroll says. "This myth is entirely in their heads."
That means sugar "crashes" could be a myth, too, though there doesn't seem to be as much of a scientific literature on it. Insulin levels, which control glucose (blood sugar) in the body, would adjust quickly after a massive intake of sweets. If there's no "high" level of glucose in the body to start with, there shouldn't be a crash or withdrawal later.
"The body works hard to keep glucose levels pretty regular, Carroll said.