Teens who play video games before bedtime go to bed later and those who use online social media take longer to fall asleep, according to a recent study.

These technology-related behaviors were tied to shorter and poorer sleep for teens on school days and even on vacation, while kids who stuck to non-tech behaviors like spending time with family before bed tended to get more sleep.

"The effects of technology and video gaming on sleep have previously been reported, so we were not surprised to see that video gaming before bed was associated with later bedtime and shorter sleep duration," said senior author Bei Bei, of Monash University and the University of Melbourne in Australia.

But this study also accounted for kids' "chronotype" - whether they tend to be more alert at night or in the morning - Bei said.

"We were able to see whether some behaviors had an effect on adolescents' sleep beyond their chronotype," she told Reuters Health by email. "The only technology that had such an effect was video gaming."

Teens may be engaging in some activities because they are not yet sleepy, and they do so to pass time until they feel like going to sleep, she noted.

"This highlights that biological factors such as natural delay in body clock, and having to get up early for school, have much stronger effects on adolescents' sleep than technology itself," Bei said.

The researchers recruited 146 adolescents in Melbourne who wore activity monitors for the last week of a school term and for two weeks of vacation time.

The teens completed pre-bedtime behavior questionnaires that assessed 25 activities like reading a book or web browsing.

On vacation days, the teens spent less time doing school work, listening to music, performing personal hygiene, web browsing and using social media before bedtime, according to their questionnaire results. They also watched more television and DVDs and spent more time with friends on vacation days.

On school days, spending time with family was tied to earlier bedtimes and longer sleep duration, while snacking predicted later bedtimes and video games predicted less total sleep, as reported online February 11 in the Journal of Adolescent Health.

"We speculate that the addictive nature of video gaming might make adolescents (keep) playing even though they might be sleepy and in need of sleep," Bei said.

On vacation days, online social media use was tied to taking longer to fall asleep, as teens were more awake and stimulated later at night.

"During vacation, none of the technology was associated with shorter sleep time, because adolescents were able to sleep in later," Bei said. "However, we found that social media was associated with somewhat longer time to fall asleep, and this might be due to social media being mentally alerting and emotionally engaging, so it's harder for adolescents to wind down quickly afterwards."

For teens who routinely do not get enough sleep on school days, sleeping later on weekends and vacation days doesn't truly "make up for it," said Dr. Shahrad Taheri of Weill Cornell Medicine - Qatar in Doha, who was not part of the new study.

"People don't make up their lost sleep," Taheri told Reuters Health.

Social media use in particular, which comes in discrete packets like texts, can interrupt the winding-down process before falling asleep and keep teens awake longer, he said. Spending time with family in person tends not to come in packets or to interrupt falling asleep, he said.

"The key to help adolescents get better sleep is to help them get sufficient sleep during school days," Bei said.

"So with the constraint of early school start time, what adolescents could do is set reasonably early bedtime, and avoid staying up late," she said. "If they feel that they are getting reasonable amount of sleep during school days (e.g., waking up feeling refreshed, alert during the day), it would be helpful to stick to the same schedule on non-school days too, and this includes both weekends and vacation."

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