WEDNESDAY, Sept. 2, 2015 (HealthDay News) -- New research offers a compelling reason for parents to ban smartphones, tablets and laptops in their children's bedrooms at night: The bright light of these devices may lower levels of melatonin, a hormone that prompts sleep.

The effect was most pronounced for kids just entering puberty, with nighttime melatonin levels suppressed by up to 37 percent in some cases, the investigators found.

With a recent study suggesting that 96 percent of teens use at least one high-tech device in the hour before bedtime, the researchers have a suggestion for parents.

"The message is that we really have to be careful about protecting our especially young teens from light at night, which means parents need to get all screens out of the bedroom, because ultimately they can be quite damaging to a child's capacity to get enough sleep," said study co-author Mary Carskadon. She is a professor of psychiatry and human behavior at Brown University's Alpert Medical School, in Providence, R.I.

Puberty and changing sleep habits go hand-in-hand, the study authors noted, as growing kids start to push for later bedtimes.

To some degree, the shift is likely prompted by several social factors, including the loosening of parental restrictions, budding friendships and media. But scientists believe that biological factors also play a role, as a child's internal sleep clock starts to change.

At the heart of that change is light sensitivity, said Carskadon, who's also director of the Sleep and Chronobiology Research Laboratory at the E.P. Bradley Hospital. Her team theorized that puberty increases a child's sensitivity to light at night, causing melatonin levels to stay low and delay sleep.

But the researchers also suspected this natural process could be knocked out of whack when newly light-sensitive children are around the bright glare of modern technology.

So the study authors focused on 38 children between the ages of 9 and 15 (early puberty), along with 29 boys and girls between the ages of 11 and 16 (later or post-puberty).