Lights out is going to take on a whole new meaning.

By Liz Steelman
Updated August 26, 2015
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Ninety-six percent of teens use at least one form of technology in the hour before going to bed, according to a recent study. And research suggests it could be hurting their sleep. But if you're the parent of a pre-teen, you might want to be even more careful. New research from Brown University suggests that the sleep cycles of tweens going through puberty are more sensitive than their older peers' when it comes to any source of pre-bed light (including, but not limited to, electronics).

For the study published in the Journal of Clinical Endocrinology & Metabolism, 38 children in early to middle puberty ranging between the ages of 9 and 15 years old, and 29 11- to 16-year-olds in late to post puberty, were exposed to varying light levels for one hour on consecutive nights. Melatonin (a sleep hormone) production was then measured through a saliva sample taken every 30 minutes.

Dim lighting suppressed melatonin by 9.2 percent for early teens, but not at all for their older peers. Normal room lighting weakened production by 26 percent and 12.5 percent, respective to age. And when exposed to approximately the strength of supermarket lighting, melatonin reduced by 36.9 percent for the tweens and 23.9 percent for the teens. Surprisingly the results were consistent across gender.

According to the Sleep Foundation, darkness signals the brain to produce melatonin, the natural hormone that tells the body it's time to sleep. Melatonin levels remain elevated throughout the night, then become barely detectable during the day. When production is disrupted, the circadian rhythm is too.

“Students who have tablets or TVs or computers—even an ‘old-school’ flashlight under the covers to read—are pushing their circadian clocks to a later timing,” senior study author Mary Carskadon said in a statement. “This makes it harder to go to sleep and wake up at times early the next morning for school.”