CBS Local — Have you ever felt the tiring effects of a “food coma” or “sugar crash” after eating candy or a big meal? According to researchers in New Zealand, simple sugars really do slow a person’s brain down and makes you lose focus.

A team from the University of Otago tested 49 people to see how three common sugars found in sweeteners, juices, and candy affected a person’s cognitive abilities. “Our study suggests that the ‘sugar coma’ – with regards to glucose – is indeed a real phenomenon, where levels of attention seem to decline after consumption of glucose-containing sugar,” lead author Mei Peng told PsyPost.

Glucose, or simple table sugar, was found to have the worst effects on each participant when they were given a series of tests to rate reaction time, attention, and memory. Researchers say the other two sugars tested, fructose (fruit sugar) and sucralose (an artificial sweetener), did not have the same negative effects on a person’s mind after being ingested.

“While the sample size is relatively small, the effect we observe is substantial,” Peng added. “This will help us better understand how attention deficits arise after glucose consumption.”

Older studies have argued the opposite effect however, claiming that consuming glucose can actually help the elderly focus and perform mentally challenging tasks more effectively.