Caffeine-drinking teens are likely to stay up late at night and doze off during the day, according to a new study.
The researchers said that web surfing, text messaging and gaming are keeping the kids up for hours into the night.
Drexel University's Dr. Christina Calamaro, assistant professor in Drexel's College of Nursing and Health Professions and researchers Mason B. Thornton and Sarah Ratcliffe asked 100 middle and high school students aged 12 to 18 to complete a questionnaire to measure nighttime intake of caffeinated drinks, use of media-related technology and sleep patterns.
The majority of the sample used some form of technology, with 66 percent having a television in their bedroom, 30 percent a computer, 90 percent a cell phone and 79 percent an MP3 digital audio player.
During the study, at least 30 percent of teenagers reported falling asleep during school.
Caffeine consumption tended to be 76 percent higher among those who fell asleep and most teenagers used multiple electronic media late into the night and consumed a variety of caffeinated beverages, including many popular energy drinks marketed to their age group.
"Many adolescents used multiple forms of technology late into the night and concurrently consumed caffeinated beverages," said Calamaro.
"Their ability to stay alert and fully functional throughout the day was impaired by excessive daytime sleepiness," he added.
At least 85 percent of those studied reported drinking caffeine. For those, the average caffeine intake was 144 mg with a range from 23 to1458 mg.
Only 27.5 percent consumed less than 100 mg of caffeine daily or the equivalent of drinking a single espresso, whereas 11.2 percent drank more than 400 mg daily or the equivalent of four espressos.
The findings are published in Pediatrics, the official journal of the American Academy of Pediatrics.