Ten volunteers were observed in the study, published in the journal Human Psychopharmacology: Clinical and Experimental. Scientists had the participants restrict their sleep to five hours the previous night. The next day, an hour after a light lunch, they gave half the group an energy drink, and the other half an identical zero-sugar drink.
Researchers found that sugar did cause a brief surge of energy in participants who got the mid-afternoon buzz; but after an hour their reaction times slowed, and they had more lapses in concentration than the group that received no sugar. They also found that although the energy drink provoked an initial physical response, their study showed no evidence that it increased mental alertness.
Although caffeine may be a quick fix for drivers and others who don't get enough sleep, Professor Jim Horne, head of the Sleep Research Centre at the University of Loughborough, says that "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."
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