How tweens use their electronic devices before bedtime can have a major impact on how well — and how long — they sleep, according to a new study . The study involved nearly 9,400 11- and 12-year-olds who are part of the Adolescent Brain Cognitive Development Study , a large, long-term study of brain development and child health in the United States. Researchers asked the tweens and their parents detailed questions about how they used screens around bedtime and how well they slept; the researchers then followed up a year later.
A majority of the tweens in the study — 72% — had their own cellphone. One surprising finding: Silencing phone notifications before bedtime was associated with less sleep than turning off the phone completely, says Dr. Jason Nagata , an associate professor of pediatrics at the University of California, San Francisco, who led the study.
"So if your phone is not completely off, teens may still be woken up overnight by vibrations or lights," Nagata says. "Or if they have any difficulty falling asleep, it might be easier for them to just check their phones if they're bored or have any sleep disruption." One out of five tweens in the study reported checking their phones if they woke up overnight, which Nagata says can lead them to become more awake or aroused, making it harder to fall back asleep.
He says a better strategy is to keep smartphones out of the bedroom altogether overnight: The study found that adolescents who did so got more and better-q.