Devices with small screens such as smartphones can give children wide access to the Internet, texts and email at almost anytime they wish.
The study, published in Pediatrics, found that children who slept near a small screen experienced shorter sleep duration and reported they did not get enough sleep.
Inadequate sleep is potential risk factor for health problems such as obesity, coronary heart disease, hypertension and stroke. For children, improved sleep can also have a positive impact on psychosocial health and school performance. Unfortunately, studies have shown that the sleep duration of children has declined steadily over the course of the past century.
Could the proliferation of modern technology be to blame for this? American youths are now consuming media for the same amount of time that the majority of adults spend working, according to background information in the study.
As well as older technology such as televisions becoming cheaper, newer technology such as smartphones are now almost ubiquitous, to the point where many children own one. These allow children to access games, music, the Internet, texts and email at any time they wish.
"Despite the dramatic increase in the use of small screens, few studies have examined children's use of small screens in relation to sleep duration," write the authors of the study.
Previous studies have linked the presence of a TV in a child's bedroom and TV viewing to reduced sleep duration and later bedtimes. Such findings could be a result of TV use replacing sleep time, increasing mental stimulation, or by screen light disrupting circadian rhythms.
However, the researchers suggest that devices with small screens such as smartphones could potentially have an even more disruptive effect. Not only are they easier to access and more interactive than TVs, small screens are typically held close to the face. Light from small screens could affect melatonin release more strongly than TV light, which weakens over distance.
In addition to these factors, small screen devices can provide audible notifications that may interrupt sleep, indicating new emails or text messages even when not in use.
Do small screens equal small amounts of sleep?
"[We] sought to examine association of small screens and TVs in children's sleep environments and reported screen time with children's sleep duration, perceived insufficient rest or sleep, and usual bedtimes and waketimes," write the authors.
For the study, the researchers assessed 2,048 participants of the Massachusetts Childhood Obesity Research Demonstration Study (MA-CORD), analyzing data collected in 2012 and 2013. Participants were fourth- and seventh-graders attending public schools in two cities in Massachusetts.
The children completed questionnaires asking them when they usually went to bed during the previous week, when they usually woke up in the morning, and how many days during the past week they felt as though they needed to have more sleep.
Alongside these questions, participants stated whether they slept close by "devices to play games or send text messages or chats to their friends like cell phones, smartphones, and the iPod Touch." The researchers also asked whether there was a TV in the room the participants slept in, as well as how much time the participants spent weekly watching TV, DVDs or playing video games.
The researchers found that a majority of participants reported sleeping near devices with small screens (54%) and in a room with a TV in (75%). Seventh-graders were more likely to sleep near a small screen device (65%) than fourth-graders (46%).
Results 'caution against unfettered access' to small screens
Independent of sleeping in a room with a TV, children that slept near a small screen got 20.6 minutes less sleep each weekday compared with children that never slept near a small screen. Sleeping close to a small screen was associated with an average delay to bedtime of 37 minutes.
Sleeping near a small screen but not in a room with a TV was also associated with an increased prevalence of self-reported insufficient sleep. This increased with each additional day of sleeping close to a device with a small screen.
Sleep was also found to be affected by watching TV, DVDs or playing video games. The researchers observed these activities to be associated with both shorter weekday sleep durations a high prevalence of perceived insufficient sleep.
"Children who slept near a small screen and those with more screen time were more likely to have perceived insufficient rest of sleep in the past week," report the researchers.
The study is limited by a cross-sectional design that prevents the authors from proving any causation. Self-reporting from the participants and a lack of measuring for potential confounders such as parenting styles and child schedules necessitate further research to support the study's findings.
"Although longitudinal and experimental studies are needed to confirm these associations, our findings caution against children's unfettered access to screen-based media in their rooms," the authors conclude.
This study could give parents cause to get their children to put certain holiday gifts away, especially in combination with other research. Last month, Medical News Today reported on a study finding that a chronic lack of sleep could dramatically increase the risk of a child being obese by the age of 15.