Many teens wired, caffeinated well past bedtime

By Anne Harding

NEW YORK (Reuters Health) - Caffeine-fueled teens are texting, Web-surfing and gaming for hours into the night, which is affecting their alertness and ability to function during the day, a new study in Pediatrics shows.

"They're up at night and they're dong a lot less homework than we thought and a lot more multitasking," Dr. Christina J. Calamaro of Drexel University in Philadelphia, the lead researcher on the study, told Reuters Health.

She and her colleagues found that he more multitasking a teen did, the more likely he or she was to be dozing off during the day, while the kids who nodded off were also the heaviest caffeine consumers.

Experts believe that teenagers need at least nine hours of sleep every night, Calamaro and her team note in their report, but the average sleep time for US adolescents is seven hours. The researchers investigated whether teens' use of technology and caffeinated beverages might affect how much sleep they got at night and how tired they felt during the day by surveying 100 12- to 18-year-olds.

To gauge how heavily the study participants used technology at night, Calamaro and her colleagues developed a measure they dubbed the "multitasking index": the total number of hours a child spent doing each of nine different activities (watching TV, listening to MP3s, doing homework, and watching DVDs or videos, etc.) divided by 9 -- the number of hours from 9 p.m. to 6 a.m.

Kids' average multitasking index was about .6, meaning they were engaged in the equivalent of one of the nine activities for 5.3 hours or four activities for an 80 minutes each.

Just one in five of the study participants said they got 8 to 10 hours of sleep a night, and these teens had an average multitasking index of 0.39.

One third of the study participants said they fell asleep in school, and these teens dozed off an average of twice a day, although some said they fell asleep as many as eight times a day. The higher a child's multitasking index, the more likely he or she was to fall asleep in school.