The Science of Screens and Sleep
During the summer, when I was a kid, I remember waiting for my parents to say goodnight before turning on the radio on the nightstand next to my bed. I'd tune the knob to the Cardinals baseball game on KMOX 1120 AM and quietly listen to as much of the game as I could before I fell asleep. I'm sure it wasn't great for my sleep, but the technology was too tempting. Just imagine being able to hear Ozzie Smith's at bat while lying in your bed!
Okay, so it doesn't sound terribly amazing now. But the point is that technology (especially the kind with a screen) is super-stimulating for kid brains and far more tempting today than a crackly radio. Everyone knows that too much screen time in general can be harmful for kids in a variety of ways, but I want to focus specifically on sleep and talk about some reasonable ways to help your kid. The stakes are high with sleep - not getting enough makes your kid more likely to be overweight, get lower grades, struggle to control emotions (I probably don't need to tell you that), and become depressed.
The scope of the problem is huge. One 2015 study found that 75% of kids between the ages of 6 and 17 have some sort of screen-based media in their bedrooms when they go to bed at night. (1) TVs used to be the biggest culprit, but now it's tablets for younger kids and phones for older kids. Those screens have been consistently linked with poorer sleep. A 2015 review, for example, looked at over 60 studies of screens and sleep. Over 90% of the studies found that screens cause delayed bedtimes and less total sleep time. (2) Perhaps unsurprisingly, computers and smartphones had a bigger negative impact than screens.
How do screens wreck our kids' sleep? Well, in a few different ways. First, seeing light at night suppresses melatonin, a natural hormone that gets our bodies ready for sleep (that whole circadian rhythm thing). A general rule is that kids' brains are more sensitive to everything than adult brains, and indeed one study found that melatonin suppression due to screens is almost double for kids compared with adults. (3) Also, even when kids do finally fall asleep after screen use, their excited brains have a harder time getting quality sleep: a recent study showed that screens at bedtime reduce restful REM sleep and also decrease morning alertness to the point where it takes several hours to catch up with those who didn't use screens the night before. (4)
In my practice, most of my teens don't get enough sleep. They are busy to be sure, but their phones are the biggest single problem. Screens are simply too tempting for all of us. We can't resist them. Think about it - when a new facebook alert pops up on your phone, it's probably an old grade school acquaintance posting about her kid's gymnastics participation trophy. But you click on it, because there's always a chance that it could be a long-lost friend who wants to reconnect. And you have way more self-control than your teen, who can't fall asleep because each "ding" could be a text from the girl he likes.
So you need a family plan to stay away from screens starting at least an hour before bedtime. For younger kids and their tablets, this should be an easy rule. But it's tougher for tweens and teens who get shaky without their phones; I've found it works best to have everyone put their phones in the kitchen to charge at night. When I suggest this, teens start to squirm as their parents slowly nod their heads. They usually then blurt out, "But I use my phone as my alarm, so. . ." I then educate them about these cutting edge alarm clocks with a big bright digital display that you can plug right into an outlet! They always appreciate that. If all else fails, I pull out my flip phone right there in the exam room to show them how I roll. That usually stuns them into submission.
1. Sleep in the modern family: protective family routines for child and adolescent sleep. Buxton OM et al. Sleep Health. 2015;1(1):15-27pmid:26779564.
2. Screen time and sleep among school-aged children and adolescents: a systematic literature review. Hale L, Guan S. Sleep Med Rev. 2015;21:50-58pmid:25193149.
3. Influence of light at night on melatonin suppression in children. Higuchi S et al. J Clin Endocrinol Metab. 2014;99(9):3298-3303pmid:4840814.
4. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Chang AM et al., Proc Natl Acad Sci USA. 2015;112(4):1232-1237pmid25535358.