Children who consume heavily sweetened energy drinks are more likely to be hyperactive, according to a recent study.

Researchers at Yale University found that middle school children who drink energy drinks are 66 percent more likely to be at risk for hyperactivity and inattention symptoms. The finding has implications for school success and lends support to existing recommendations to limit the amount of sweetened beverages schoolchildren drink.

"As the total number of sugar-sweetened beverages increased, so too did risk for hyperactivity and inattention symptoms among our middle-school students. Importantly, it appears that energy drinks are driving this association," Jeanette Ickovics, who led the study, said in a statement. "Our results support the American Academy of Pediatrics recommendation that parents should limit consumption of sweetened beverages and that children should not consume any energy drinks."

For the study, researchers surveyed nearly 2,000 middle school students randomly selected from a single urban school district in Connecticut.

They found that boys were more likely to consume energy drinks than girls and that black and Latino boys were more likely to drink the beverages than their white peers. The average age of the student participants was 12.4 years old. The study controlled for the number and type of other sugar-sweetened drinks consumed.

Previous studies have shown a strong correlation between children with attention deficit hyperactivity disorder (ADHD) and poor academic outcomes, greater difficulties with peer relationships, and increased susceptibility to injuries. 

Some sugar-sweetened beverages and energy drinks that are popular with students contain up to 40 grams of sugar. The students in this study consumed on average two sugared drinks per day, with a range of zero to seven or more drinks. Health experts recommend that children consume a maximum of 21 to 33 grams of sugar daily (depending on age).

In addition to hyperactivity and inattention, heavily sugared beverages also impact childhood obesity, noted Ickovics, and sugar-sweetened beverages are a leading cause of added calories in the diets of obese children. Currently, about one-third of American schoolchildren are considered overweight or obese.

The findings are detailed in the journal Academic Pediatrics.