When children and teens have smartphones and tablets in their bedrooms, the amount and quality of their sleep deteriorates significantly, and their daytime sleepiness increases, according to a study published online this week in the journal JAMA Pediatrics.
In fact, even when the devices are present in the young people’s rooms but not in use, they hinder the ability of children and teens to get a proper night’s rest, the study found.
Although plenty of previous studies have shown that the use of conventional electronic devices — televisions, gaming consoles and computers — negatively affect sleep, this is the first major analysis of the effects of smartphones and other screen-based mobile devices on children’s sleep, say the study’s authors.
These new findings are troubling — for a couple of reasons. First, sleep is essential for children’s mental and physical wellbeing. As background information in the new study points out, children who do not get enough sleep are at increased risk of developing eating disorders, obesity, reduced immunity, stunted growth, depression and substance abuse.
They’re also more likely to do poorly in school.
Second, most young people in the United States — 72 percent of children and 89 percent of teens — have at least one smartphone, tablet or other media device in their bedroom, according to surveys by the National Sleep Foundation.
Among high-school-aged teens (those 15 to 17 years old), more than two-thirds leave their devices on while sleeping, and 43 percent wake up in the middle of the night to either read or send text messages.
For the JAMA Pediatrics study, a team of British and American researchers, led by biostatistician Ben Carter of King’s College London, searched for studies published on this topic between January 2011 and June 2015. They found 467 such studies, but focused on 20 cross-sectional studies involving 125,198 children and adolescents between the ages of 6 and 19. (A cross-sectional study collects data at a specific point in time — such as media use in the bedroom and amount of time spent sleeping.)
An analysis of the pooled data from those 20 studies showed “a strong and consistent association between bedtime media device use and inadequate sleep quantity, poor sleep quality, and excessive daytime sleepiness,” write Carter and his colleagues.
Children and teens who used media devices at bedtime were, for example, more than twice as likely as their peers to not get enough sleep and to feel sleepy during the daytime.
Interestingly, even when children and teens did not use the devices at night, but simply had them in their rooms, their odds of getting a poor night’s sleep increased by about 50 percent, and their odds of being excessive sleepy during the day more than doubled.
Limitations and implications
Cross-sectional studies are observational, which means they cannot prove that one thing causes another. Also, the data from these studies were self-reported, mostly by parents, and such self-reports are not always accurate.
Still, the findings from this new meta-analysis support other types of research regarding screen-based devices and sleep.
A recent report from the American Academy of Pediatrics (AAP) describes severals ways in which the use of these devices around bedtime interferes with children’s sleep. One is by suppressing (due to the blue light emitted by the screen) the release of the hormone melatonin, which plays an important role in signaling to the brain that it’s time to sleep. (Blue light-blocking features now available on some mobile devices may — or may not — help. More research is needed to determine their precise effect on sleep.)
In addition, mobile devices provide socially stimulating material that children often find difficult to resist.
“Children frequently have a fear of missing out if they disconnect,” explain sleep researcher Dr. Charles Czeisler and pediatrician Dr. Theresa Shanahan in a commentary that accompanies the study. “Coupled with the demands of homework, media devices can keep children and adolescents awake well past the bedtime needed to obtain an adequate amount of sleep.”
“Delays in sleep initiation can set off a reinforcing physiological cascade to further delay sleep onset and restrict sleep duration on subsequent nights,” they add. “This situation is exacerbated during the school year, when weekday school start times and weekend athletic competition and other extracurricular activities often require an early start to the day.”
The AAP recommends that children and teens not sleep with screen-based devices in their bedrooms, including TVs, computers and smartphones, and that they avoid exposure to devices or screens for one hour before bedtime.
Parents, take note.
FMI: The meta-analysis and the accompany editorial can be found at the JAMA Pediatrics website. Parents may want to check out the AAP’s online “Family Media Plan” tool, which can help you develop a media plan that fits the specific needs of your family.