The presence of a television in a child's bedroom can have detrimental effects on sleep quality and duration.

However, relatively few studies have assessed the potential detrimental effects of smaller screens, such as those on handheld devices. In addition to the light from screens and the potential alterations of sleep cues that might be induced by the light, handheld devices or tablets can also alarm with emails or texts, potentially creating even more sleep disruption.

This study assessed seventh- and fourth-grade children in public schools in Massachusetts to correlate nocturnal screen use with perceived sleep sufficiency. The data were collected in 2012 as part of a statewide obesity research effort. There were two primary outcomes of interest. One was the children's weeknight sleep duration.

The second outcome was a measure of whether the children perceived that they had received sufficient sleep during the previous week. Sleep duration was calculated by subtracting the child's usual weeknight bedtime from reported usual weekday awakening times. Sleep adequacy was assessed by asking the students about how many days in the past week they felt that they needed more sleep.

This response was dichotomized into those who indicated that they needed more sleep on 3 or fewer days per week (sufficient sleep) vs those who needed more sleep on 4 or more days per week (insufficient sleep).

The students were asked how often they slept with a device near their bed, and they again responded with the number of days per week. They also indicated whether they had a TV in the room.

Analyses accounted for sex, grade in school, race/ethnicity, and reported physical activity. Complete data were provided by 2000 students (mean age: 10.6 years; 40% Hispanic, 38% non-Hispanic white, 10% non-Hispanic black). Slightly more than half (54%) of the students reported sleeping near small screens, and 75% slept in a room with a television.

When looking at differences by grade, 65% of the seventh graders slept near a small screen compared with 46% of fourth graders. The seventh graders reported a mean sleep time of 8.8 hours compared with 9.8 hours for the fourth graders. Children who slept near a small screen averaged 20.6 fewer minutes of sleep per night (95% confidence interval, 29.9-11.4) compared with those who did not sleep near a small screen. A similar association was seen in children who slept with a television in the room.

The differences in sleep among the groups were mainly accounted for by a delay of bedtime.

When looking at the effects on perceived sufficiency of sleep, the prevalence ratio for sleeping near a small screen was 1.38, indicating that the presence of a small screen was associated with a higher prevalence of reporting insufficient sleep.

Demographic variables did not generally correlate with reports of insufficient sleep. Even among those exposed to small screens, the duration of screen time was associated with a greater prevalence ratio of reporting insufficient sleep. The investigators concluded that sleeping in proximity to a small screen, having a television in the bedroom, and longer duration of screen time were all associated with shorter sleep durations. Presence of a small screen (but not a TV) and longer screen time were associated with perceived insufficiency of sleep.

Source: William T. Basco, Jr, MD, MS, http://www.medscape.com/viewarticle/839529