The so-called sugar rush is merely a product of your imagination.

We've all encountered the idea of the 'sugar rush.' It’s a notion that has led parents and even teachers to take candy away from children, fearing they’ll become overly energetic and uncontrollable. This misconception has been ingrained in American culture for years—and it’s not just kids who face it. Adults, too, are cautious about sugar. Some of this caution is understandable—due to concerns like diabetes and the obesity crisis—but the reality is that sugar doesn’t lead to hyperactivity. Its effects on the body aren’t so dramatic. The science is clear: there's no such thing as a 'sugar rush.'

To understand how and why this myth originated, we have to travel back to a time long before World War I—and then take a detour through the 1970s.

The Complex Nature of Our Relationship with Sugar

Cultural historian Samira Kawash notes that America has had a longstanding, complicated relationship with sugar. In her book Candy: A Century of Panic and Pleasure, Kawash explores how candy evolved from a simple treat to an everyday food during the early 20th century. At that time, scientific dietary guidelines recommended a mix of carbs, proteins, and fats, with sugar seen as a key energy source.

Not everyone was convinced: The temperance movement, for instance, argued that sugar could have effects similar to alcohol, causing candy-eaters to become lethargic, dizzy, and overly excitable. In 1907, the head of the Philadelphia Bureau of Health claimed that the 'appetite' for candy and alcohol were 'one and the same,' according to Kawash. On the other hand, some researchers suggested that sugar from candy could curb alcohol cravings—a notion that candy manufacturers eagerly embraced in their ads.

While the debate over sugar as an energy source raged in America, militaries worldwide were also studying sugar’s potential as fuel for soldiers. In 1898, the Prussian war office conducted the first official study on sugar—with encouraging results: 'Sugar in small amounts is well-suited to help men perform extraordinary physical labor,' early researchers concluded. German military experiments introduced candy and chocolate cakes to fortify their troops, and the U.S. military quickly followed suit, adding sugary foods to soldiers' rations. When American soldiers returned from World War I, they craved sweets, sparking a massive candy boom that continues today, as Kawash discussed on her blog, The Candy Professor. Advertisers began promoting candy as a fast, convenient source of energy for busy adults.

As artificial sweeteners started appearing in kitchens in the 1950s, candy makers struggled to appeal to women concerned about their waistlines. In 1954, one group, Sugar Information Inc., created a small pamphlet titled 'Memo to Dieters,' which fit inside chocolate boxes. 'Sugar before meals raises your blood sugar level and decreases your appetite,' the pamphlet claimed. However, by the 1970s, the era of sugar's unchallenged popularity was beginning to decline.

The Birth of the Sugar Rush Myth

The notion that sugar triggers hyperactivity gained momentum in the early 1970s when researchers began examining the potential links between diet and behavior. One of the leading figures in this area was allergist Benjamin Feingold, who theorized that certain food additives, such as dyes and artificial flavorings, could contribute to hyperactivity. He turned this theory into a widely discussed—but controversial—elimination diet. While some sugary foods were excluded from the program due to their additives, sugar itself was never outright banned. Nevertheless, thanks to Feingold's diet, sugar gradually became associated with the idea of diet-induced hyperactivity.

It wasn’t until the late 1980s that serious skepticism about the link between sugar and hyperactivity started to emerge among scientists. As FDA historian Suzanne White Junod noted in 2003 [PDF], the 1988 Surgeon General’s Report on Nutrition and Health concluded that 'alleged connections between sugar consumption and hyperactivity/attention deficit disorders in children had not been scientifically validated.' Despite the persistent 'mothers' mantra of no sweets before dinner,' she observed, 'more significant claims of adverse effects in children have not withstood rigorous scientific scrutiny.'

A 1994 study

found that aspartame—an artificial sweetener that had also been blamed for causing hyperactivity in children—had no effect on 15 children with ADHD, even though they consumed 10 times the typical amount.

The following year, the Journal of the American Medical Association released a meta-analysis exploring the impact of sugar on children's behavior and cognition. The analysis included data from 23 studies conducted under controlled conditions: In each study, some children were given sugar, while others received a placebo sweetener like aspartame. Neither the researchers nor the children knew which group they belonged to. The studies involved neurotypical children, children with ADHD, and a group of kids considered 'sensitive' to sugar by their parents.

The meta-analysis concluded that 'sugar does not influence children's behavior or cognitive performance.' (The authors did caution that 'a small effect of sugar or effects on specific subgroups of children cannot be completely ruled out.')

'Up to this point, all the well-controlled scientific studies examining the link between sugar and behavior in children have failed to show any significant connection,' says Mark Wolraich, an emeritus professor of pediatrics at the University of Oklahoma Health Sciences Center who has spent over 30 years working with children with ADHD and co-authored the 1995 paper, in an interview with Mytour.

However, the myth that sugar leads to hyperactivity persists. A major factor in this is the placebo effect, which can be remarkably powerful. The belief that consuming too much candy will cause a 'sugar rush' is similar to the hoped-for energy boost from an energy drink or a meal replacement bar (which often contains multiple teaspoons of sugar). The same principle applies to parents who claim their kids get hyperactive at parties. It’s not sugar at play, but rather peer pressure and excitement.

'The strong belief held by parents in sugar’s impact on their children’s behavior may stem from expectancy and common associations,' Wolraich noted in the JAMA paper.

It works the other way around, too: Some parents claim to notice a change in their children’s behavior once they cut down on sugar. This approach, like the Feingold diet, still garners attention and support, because the belief in its effectiveness often determines whether it actually works.

Correlation, Causation, and Caffeine

This isn’t to say there are no connections between sugar consumption and adverse health outcomes. A 2006 study found a link between high consumption of sugary soft drinks and mental health problems, including hyperactivity. However, the study was based on self-reported questionnaires completed by over 5000 10th-grade students in Oslo, Norway. The authors also noted that caffeine is commonly found in cola drinks, which could have confounded the results.

In another study, University of Vermont economics professor Sara Solnick and Harvard health policy professor David Hemenway examined the so-called 'Twinkie defense,' which suggests that sugar can lead to an 'altered state of mind.' (The term Twinkie defense originated from the 1979 trial of Dan White, who was charged with killing San Francisco city district supervisor Harvey Milk and Mayor George Moscone. His defense attorneys argued that his junk-food diet in the months leading up to the killings demonstrated a 'diminished capacity' and inability to premeditate the crime. White was convicted of voluntary manslaughter.)

In their survey of nearly 1900 Boston public high school students, Solnick and Hemenway discovered 'a significant and strong correlation between soft drink consumption and violence.' Adolescents who drank more than five cans of soda per week—around 30 percent of the group—were notably more likely to have carried a weapon.

However, Solnick tells Mytour that the study does not provide evidence of a 'sugar rush.'

'Even if sugar did cause aggression—which we did not prove—there's no way of knowing whether the effect is immediate (and possibly short-lived) as the term 'sugar rush' suggests, or if it’s a longer-term process,' she explains. For instance, sugar could increase irritability, which might sometimes escalate into aggression—but not necessarily as an immediate reaction to sugar consumption.

Harvard researchers are investigating the long-term impacts of sugar using data from Project Viva, a large observational study involving pregnant women, mothers, and their children. A 2018 study published in the American Journal of Preventive Medicine examined over 1200 mother-child pairs from Project Viva, analyzing the mothers' self-reported diets during pregnancy and the health of their children during early childhood.

'Sugar consumption, particularly from [sugar-sweetened beverages], during pregnancy and childhood, and maternal diet soda consumption may negatively affect child cognition,' the study's authors concluded, though they acknowledged that other factors might account for the observed link.

'This study can examine relationships, but it cannot establish cause and effect,' says Wolraich, who was not involved in the research. 'It’s equally plausible that parents of children with lower cognition may be more likely to have higher sugar or diet drink consumption, or that a third factor is influencing both cognition and consumption.'

The Science of the Sugar Crash

While the evidence against the sugar rush is compelling, the 'sugar crash' is real—but it typically only affects individuals with diabetes.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, low blood sugar—or hypoglycemia—is a serious medical condition. When a large amount of sugar enters the bloodstream, it can cause a spike in blood sugar levels, leading to fluctuations, instability, and eventually a crash, which is known as reactive hypoglycemia. If a diabetic’s blood sugar becomes too low, it can result in symptoms such as shakiness, fatigue, weakness, and more. In severe cases, hypoglycemia can lead to seizures or even coma.

However, for most people, this is quite rare. Dr. Natasa Janicic-Kahric, an endocrinologist, shared with The Washington Post that "only about 5 percent of Americans experience a sugar crash."

You are more likely to experience it if you engage in an intense workout on an empty stomach. "If someone exercises rigorously without taking in enough calories to replenish what they’ve used, they might feel lightheaded," says Wolraich. "However, in most cases, the body does a good job of regulating its needs."

So, what you're attributing to sugar—the highs and the lows—is probably all in your mind.