"This issue has never been raised in a public forum," says Dr. Charles P. Pollak, a professor of neurology at Ohio State University who reports the study in the January issue of Pediatrics. "In the past, the availability of soda has been criticized on a nutritional basis, the empty calories they contain. Our findings suggest that an issue to be considered would be the caffeine content of soft drinks."
Pollak's study enrolled 191 students in the seventh, eighth, and ninth grades, who kept diaries of their intake of caffeine-containing foods and beverages and their sleep time for two weeks. "Higher caffeine intake in general was associated with shorter nocturnal sleep patterns, increased wake time after sleep onset and increased daytime sleep," the journal report says. This isn't a critical problem, Pollak acknowledges. "We're not raising a major alarm, but it is worthy of investigation," he says.
It appears that only a small percentage of teenage students consume enough caffeine-containing soft drinks to affect their school performance, and "there is no estimate of how prevalant the problem might be," Pollak says. "But before schools install soda machines or continue allowing their use, one of the things to be considered is the possible effects of caffeine," he adds.
What would be needed to clinch -- or disprove -- the case against soft drinks would be a carefully controlled study in which sleep patterns and school performance would be judged against the amount of caffeine intake of young people, Pollak says. "I think such a study is feasible," he says.
It's a false alarm, says Sean McBride, a spokesman for the National Soft Drink Association. "It's really very difficult to tell from this study what the impact on caffeine intake is on teenagers," he says. "There really is no way to tell whether caffeine or other factors are responsible for those interrupted sleep patterns."
The journal report says there are "a lot of deficiencies and limitations" of the study, such as the small number of students and lack of independent verification of caffeine intake, McBride says.
But the industry does recommend wise drinking habits, he adds. "Our advice is that all beverages should be consumed in moderation. And if there are any concerns about health, including sleep patterns, you should consult your family doctor or appropriate health care provider," McBride says.
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