August 14, 2019
Adequate sleep paired with limits on screen time helps reduce impulsivity in children, a study suggests.
Michelle D. Guerrero, PhD, with the Healthy Active Living and Obesity Research Group at Children's Hospital of Eastern Ontario Research Institute, in Canada, and colleagues say the study, published online August 14 in Pediatrics, is the first to demonstrate the combined association. Previous studies have investigated movement factors individually, Guerrero told Medscape Medical News.
The results may add scientific reinforcement to physicians' advice to parents of children, Guerrero said, and help them zero in on two factors that can make a difference, because few children (17.7%) in the study met both screen and sleep recommendations.
"We need to be especially mindful of how long kids are on their devices and bedtime," she said.
The researchers compared children's answers to survey questions against the Canadian 24-Hour Movement Guidelines for Children and Youth, the first evidence-based movement guidelines with a full-day scope.
The guidelines recommend 9 to 11 hours of sleep nightly, no more than 2 hours of daily recreational screen time, and at least 60 minutes of moderate to vigorous physical activity every day.
The authors gathered data on 4524 children between the ages of 8 and 11 years who answered (or whose parents answered) questions in the Adolescent Brain Cognitive Development (ABCD) study, a longitudinal, observational study on children's brain development and health that is conducted periodically in the United States. The researchers assessed whether the children's behaviors met the Canadian guidelines and whether adherence affected impulsivity.
Three Factors Tested for Effect on Impulsivity
The authors studied the effect of adequate sleep, limited screen time, and physical activity on impulsivity in children. Sleep and screen limits together had a particularly strong association with impulse control.
Guerrero said, "Right now, we know that meeting all three is certainly beneficial, but meeting the screen time and the sleep seem to be driving the relationship."
That combined effect is not completely surprising, Guerrero told Medscape Medical News, because if children are not sleeping, they are often using their devices, so limits on bedtime and screen use work well together.
For the ABCD study, parents were asked to record the hours the child slept most nights. Children were asked to report hours spent engaging in screen-based activities, such as watching shows and movies and texting, on a typical weeknight and weekend day. Physical activity was determined by children's answers on the Youth Risk Behavior Survey as to how many days they were active for at least an hour a day in the past week.
How Impulsivity Was Measured
Impulsivity was determined from children's answers on four assessment tools: the UPPS-P Impulsive Behavior Scale; the Behavioral Inhibition System (BIS); the Behavioral Activation System (BAS) Scale; and a delayed-gratification assessment involving a choice in the way they would prefer to get cash (whether they would prefer getting $75 in 3 days or $115 in 3 months.)
Children were asked to rate sentences such as, "I do everything to get the things I want" or "I crave excitement and new sensations" or "I feel worried when I have done poorly at something" from 1 to 4 according to how closely those statements matched their feelings.
"Scores on the UPPS-P and BIS/BAS scales have been shown to have adequate reliability coefficients, and the delay-discounting task has correlated well with real monetary rewards," the authors write.
Guerrero said that in future studies, rather than relying on self-report, they would like to track the movement factors with objective tools, such as accelerometers or screen time monitoring systems, to eliminate possible recall bias.
Guerrero suggested that, given these findings, parents should be encouraged to restrict screen time, especially 1 to 2 hours before bedtime, so children's minds and bodies can prepare for sleep. Parents can also create a tech-free bedroom zone, she said.
The study was funded by the National Institutes of Health. The authors have disclosed no relevant financial relationships.