A number of factors contribute to making pre-bedtime media use far more damaging to kids than it is for adults.
If you're a parent, you have probably heard the message that too much screen time can affect children's quality of sleep. But what's less understood is exactly why digital media undermines sleep. A group of researchers from the University of Colorado, Boulder, have tried to answer this question in a new study just published in a supplemental issue of Pediatrics. The team, led by Monique LeBourgeois, found three main causes for sleep disruption:
First, there's the impact of light. Children's bodies are far more sensitive to light than adults' bodies are, which means they're susceptible to greater sleep disruption when exposed to screens in the hours leading up to bedtime. LeBourgeois told CU Boulder Today:
"Light is our brain clock’s primary timekeeper. 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."
The authors cited a study in which children, when exposed to the same amount and intensity of light as adults, saw their melatonin levels drop twice as much as the adults. Melatonin is the hormone required to regulate sleep.
Ironically, many parents "incorporate digital media into the bedtime routine as a means of calming children down before sleep" -- clearly a bad idea. Read a book instead?
Second, there's the psychological stimulation that comes with using digital media. Even adults can relate to this, but the feeling is even more intense for children. Says LeBourgeois:
"Whether it’s exposure to violent media, playing an exciting game or texting back and forth with friends, all these interactions increase cognitive arousal, which can in turn decrease sleepiness."
This is where parents need to the draw line, limiting online activity in the pre-bedtime hours and knowing exactly what the kids are watching or doing.
Third, using digital media means time spent not doing other things. This is also known as 'time displacement.' Kids with constant access to handheld devices will be inclined to use them, which results in less time for play and exercise, interacting with family, conversation, schoolwork, and, obviously, sleeping. The problem is made worse when phones and tablets accompany kids into the bedroom. These should be confiscated before bed.
From the study's abstract:
"Data from a cross-sectional study of 454 adolescents revealed that >60% kept their mobile phones with them when they went to bed and >45% used their phones as an alarm, a reflection of the high prevalence of digital media in the sleep spaces of adolescents."
The conclusion? Make sleep a top priority for kids. This needs to be a focal point for parents and schools if we're serious about wanting better psychological health, improved cognitive functioning, fewer risky behaviours, and healthier body weights for our children. It echoes what neuroscientist Matthew Walker, author of "Why We Sleep," has been saying all along:
“No aspect of our biology is left unscathed by sleep deprivation. It sinks down into every possible nook and cranny. And yet no one is doing anything about it. Things have to change: in the workplace and our communities, our homes and families."