Feeling Sleepy? High Sugar, Low Caffeine "Energy Drinks" Can Make It Even Worse

An hour after consuming a high sugar, low caffeine drink you will tend to have slower reactions and experience more lapses in concentration than if you had simply drunk a decaffeinated, carbohydrate drink.

This was the finding of research performed at the University of Loughborough and published in this month's Human Psychopharmacology: Clinical and Experimental.

Ten healthy adults had volunteered to restrict their sleep to 5 hours on the day before participating in the trial. An hour after eating a light lunch they were given either an energy drink (42g sugar + 30mg caffeine) or an identically tasting zero-sugar drink. They then performed a monotonous 90-minute test during the afternoon 'dip' that assessed their sleepiness and ability to concentrate.

For the first 30 minutes there was no difference in the reaction times or error rates, but 50 minutes after consuming the drinks, the performance of those who had had the energy drink started to slip, and they became significantly sleepier.

Other researched work shows that high energy drinks that contain caffeine will boost concentration.

"A 'sugar rush' is not very effective in combating sleepiness - so avoid soft drinks that contain lots of sugar but little or no caffeine," explains Professor Jim Horne, who runs the Sleep Research Centre at the University of Loughborough. "A much better way to combat sleepiness is to have a drink that contains more useful amounts of caffeine and combine this with a short nap".

Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas and spokeswoman for the American Dietetic Association explains that simple sugars are digested, absorbed and metabolized very quickly, so the energy they contain doesn't last long.

"Some energy drinks may have just enough caffeine to stimulate your central nervous system and give you a false sense of feeling energized for a short period of time," Sandon said. "Keep in mind, a dose of caffeine large enough to have an energizing effect -- about 1 regular soda or cup of coffee -- will only last about 3 hours."