BOULDER, Colo. — If you don’t want to take a single study’s word for it, take five dozen. A review of research focusing on the effects of excessive screen time on children concludes that because their brains, sleep patterns, and eyes are still developing, they are more vulnerable to sleep disruption from staring at their phones, computer, and TVs too much.
Previous research has highlighted the negative effects that blue light from mobile devices have on the eyes in relation to sleep patterns, but this review by researchers from the University of Colorado-Boulder was a rare study that compared the toll screen time takes on adults and children. Of the 60-plus studies that the authors examined focusing on children ages 5-17, 90 percent showed a link between greater screen time and delayed bedtimes, fewer hours of sleep and poorer sleep quality.
“The vast majority of studies find that kids and teens who consume more screen-based media are more likely to experience sleep disruption,” says study author Monique LeBourgeois, an associate professor in Colorado University’s Department of Integrative Physiology, in a news release. “With this paper, we wanted to go one step further by reviewing the studies that also point to the reasons why digital media adversely affects sleep.”
The researchers cite biological, neurological, and environmental factors for screen time affecting children more than adults. Because their eyes are not fully developed, children are more sensitive to light than adults, leaving their internal clocks to be more susceptible to disruption. That’s because when light enters the retina at night, it causes a child’s body clock to hold back on the release of the sleep hormone melatonin. The researchers note that melatonin levels in children fell twice as much as adults when exposed to short-wave, or “blue” light.
“We know younger individuals have larger pupils, and their lenses are more transparent, so their exposure and sensitivity to that light is even greater than in older individuals,” says LeBourgeois.
From the collection of studies, researchers calculated that more than 75% of youths keep some form of electronic device with a screen in their rooms overnight. Sixty percent were shown to interact with them an hour before bed, and 45% even use their phones as alarms.
LeBourgeios says that parents should be aware of the impact screen time has on a child’s circadian rhythm, particularly because of how sensitive they are at night to light at a young age.
“The preschool years are a very sensitive time of development, during which, use of digital media is growing more and more pervasive. There’s a lot we don’t know about how it may shape sleep and the body clock in little kids,” she says. “Through the young eyes of a child, exposure to a bright blue screen in the hours before bedtime is the perfect storm for both sleep and circadian disruption.”
The full study was published Nov. 1, 2017 in the journal Pediatrics.