Monday, January 6, 2003
By Marilyn Elias
Jan. 7, 2003
Drinking too many caffeinated soft drinks might be preventing some adolescents from getting a good night's sleep, a study suggests.
The more caffeine children had, the less they slept overnight and the more daytime napping they did, says study leader Charles Pollak, a neurologist at Ohio State University Medical School.
It's well-known that teens often sleep too little during the week because they stay up late and leave for school early. But this is the first study that had adolescents keep diaries on sleep and caffeine intake.
In the study, published in Pediatrics, 191 students ages 12 to 15 consumed about 70 percent of their daily caffeine in soft drinks, Pollak and co-author David Bright say. An additional 20 percent came from coffee or tea and 10 percent from other foods or medications.
Kids averaged 53 milligrams of caffeine a day, a little more than in a 12-ounce can of Coca-Cola. (By comparison, a cup of coffee has 135 milligrams.) About one of five averaged 100 milligrams or more a day.
Teens slept an average 8.3 hours a night, but some slept as few as six. And as caffeine intake rose, nighttime sleep fell and daytime naps increased.
"We can't be sure the caffeine caused them to lose sleep, because the arrow might be in the opposite direction," Pollak says. "Sleepy kids may use caffeine to wake themselves up."
Also, both could be going on: daytime caffeine boosts to stay awake, followed by night insomnia, followed by a need for more caffeine the next day.
"It's an open question" whether too much caffeine can hurt children, says Sean McBride of the National Soft Drink Association, a trade group in Washington, D.C. "But soft drinks can fit into a balanced diet. People should consume all foods, including these beverages, in moderation. Also, there are caffeine-free soft drinks."
Still, some people say public schools shouldn't have soda vending machines. About seven in 10 U.S. middle and high schools have them, according to a national survey two years ago.
School districts make money off these machines, "and now it's part of their operating budget, so the schools have become addicted to soft drinks," says Yale University psychologist Kelly Brownell, a specialist in eating behaviors. "We already know about the sugar in these drinks and unhealthy calories. Now there's another concern with the caffeine. . . . There's no question they should be getting rid of these soda machines."