Kids driving you crazy this summer? It could be because they need more sleep. A new study out of the University of Virginia, Charlottesville found that four-year-olds with shorten than average sleep times have increased rates of “externalizing” behavior problems.
“Preschool children with shorter nighttime sleep duration had higher odds of parent-reported over activity, anger, aggression, impulsivity, tantrums, and annoying behaviors,” according to the new research by Dr. Rebecca J. Scharf of University of Virginia, Charlottesville, and colleagues.
The study, published in the July Journal of Developmental & Behavioral Pediatrics, the official journal of the Society for Development and Behavioral Pediatrics, analyzed parent responses from a nationally representative study of approximately 9,000 children, followed from birth through kindergarten age. When the children were four years old, nighttime sleep duration was estimated by asking the parents what time their child typically went to bed and woke on weekdays.
On a standard child behavior questionnaire, parents rated their child on six different “externalizing” behavior problems such as anger and aggression. (Externalizing behavior problems are outward behaviors, distinguished from “internalizing” problems such as depression and anxiety.) The relationship between sleep duration and behavior scores was assessed, with adjustment for other factors that might affect sleep or behavior.
The average bedtime was 8:39 p.m. and wake time 7:13 a.m., giving a mean nighttime sleep duration of about 10.5 hours. Eleven percent of children were considered to have “short sleep duration” of less than 9.75 hours (calculated as one standard deviation below the average).
On the child behavior questionnaire, 16 percent of children had a high score for externalizing behavior problems. Behavior problems were more common for boys, children who watched more than two hours of television daily, and those whose mothers reported feeling depressed.
After adjustment for other factors, “Children in the shortest sleep groups have significantly worse behavior than children with longer sleep duration,” Dr Scharf and colleagues write. The effect was greatest for aggressive behavior problems, which were about 80 percent more likely for children with nighttime sleep duration of less than 9.75 hours.
Shorter sleep times were also associated with 30- to 46-percent increases in rates of the other externalizing behaviors studied, including over activity, anger, impulsivity, tantrums, and annoying behaviors. In a linear analysis, as sleep duration increased, troubling behaviors decreased.
Previous studies in smaller groups of children have identified shorter nighttime sleep duration as a risk factor for behavior problems in preschool children. The average 10½-hour sleep time in this nationally representative sample is less than in studies performed in past decades, and less than currently recommended for four-year-olds.
The new results, along with other recent studies, add to the evidence that preschoolers who sleep less will have more behavior problems, including disruptive behaviors like aggression and over activity. Although the study can’t draw any conclusions about causality, “there is good reason to believe that short nighttime sleep duration leads to externalizing behaviors,” the researchers write.
