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Zombieland? Tech Wrecking Sleep for Scores of Teens: Study

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A smartphone user laying in bed at late night in a dark room checking the latest feeds. Artur Debat / Moment Editorial/Getty Images

Maybe they should be dubbed Generation-Zzzz.

Teens who bury their faces for hours on end in laptops, tablets, smart phones or TV screens during the days tend to suffer bad nights of sleep, researchers reported Monday.

"There are indications that today's teenagers sleep less than previous generations," said Mari Hysing, co-author and a psychologist at Uni Research Health in Norway. "There are some aspects of electronic devices that may give an additional arousal; the [screen] light may impact sleep hormone production, and also the social communication aspect" may stir adolescents to keep chatting deep into the night.

"We cannot conclude which time during the day was more detrimental [to sleep], but it seems that it is the cumulative daily amount which is important," Hysing added.

How much sleep should your teen get? 2:28

The research, published in the online journal BMJ Open, was based on the tech and sleep behaviors of 10,000 16- to 19-year-old boys and girls. They participated in the Norwegian youth@hordaland study during 2012. All were asked how much screen time they absorbed daily outside of school plus which electronic devices they used most, and when they normally went to bed, how long it typically took them to fall asleep, and when they usually arose on weekdays and weekends.

Some of the key findings:

  • If a teen's total, daytime screen time surpassed four hours, that was associated with a 49 percent higher risk of taking longer than one hour to fall asleep when compared to adolescents whose cumulative daily screen time fell below four hours.
  • Total screen viewing that exceeded two hours after school was "strongly linked" to both a longer period of tossing and turning before dreams finally came—and with shorter, nightly sleep duration.
  • Teens who used two to three devices each day were more likely to sleep for less than five hours when compared to those used just one gadget.

How unhealthy is a five-hour night of sleep for kids that age?

On Monday, the National Sleep Foundation, along with an expert panel that included pediatricians and neurologists, recommended that teenagers between the ages of 14 and 17 get eight to 10 hours of restorative sleep each night — a full hour longer than the group had previously suggested.

The precise time each day that teens spend online, listening to digital music or watching television also appears to be critical in marring or bolstering sleep patterns. Hysing and colleagues noted that use of any device in the hour before bedtime was linked to a heightened risk of taking longer than 60 minutes to get to sleep, the authors said. Tapping tech while in bed seems especially unhealthy.

"Use of electronic devices may lead to an association between the bed with wakefulness, and ideally we want the bed and the bedroom to be associated with sleep," Hysing said.

But a leading parenting expert who viewed the findings disagreed that cumulative, daily screen time is the main culprit robbing teens of sleep.

"The quantity of screen time … is an outdated concept," said Dr. Deborah Gilboa, who also specializes in youth developing. "Homework alone often requires hours of screen use, and that is unlikely to change."

Instead, a better solution would be to teach teens that screen use can, in fact, impact their sleep, and to encourage them and their families "to find a healthy balance of screen use, vigorous exercise, and non-screen relaxation in order to improve sleep and health overall," Gilboa said.

"This study points out all of the reasons that we need to evaluate screen use in teens with sleep difficulty or too little sleep with the same — or more — thoroughness with which we evaluate caffeine and other stimulant use. It's becoming more and more clear that screens are brain stimulants," Gilboa added.

What more should parents do? And what can teens do to revise their sleeping habits and grab more slumber?

Current health experts suggest that teens and kids don't have a TV in their bedrooms. The Norwegian authors want to push that change further.

"There may be other electronic devices exerting the same negative influence on sleep, such as PCs and mobile phones. The results confirm recommendations for restricting media use in general," the authors conclude. But, their study didn't allow them to place specific restrictions on cumulative daily hours of screen time.

"We recommend that the adolescents, at the least, leave their electronic devices outside the bedroom before they go to sleep," Hysing told NBC News. "In other words, we do not recommend falling asleep with the TV on or with music on your ear. Ideally, the last hour before bed should be free of electronic devices."

How to get your family's bedtime back on track 3:15