Preschoolers Who Sleep Less Have More Behavior Problems

Two- and three-year-old children sleeping less than 10 hours in a 24-hour period were consistently at greatest risk for behavior problems such as oppositional or noncompliant behavior, "acting out" behaviors, and aggression, reported the team of Northwestern University scientists conducting the study.

Preschoolers who sleep less at night have almost 25 percent greater chance of psychiatric diagnosis, according to the study, published in the June issue of Developmental and Behavioral Pediatrics.

Measuring the relationship between sleep and daytime behavior on the Child Behavior Checklist, the researchers found lower amounts of total 24-hour sleep, including daytime naps, were related to increased behavior problems. Links with anxiety, depression and other internalizing behavior problems were not significant, however, they reported.

The scientists found that specific "doses" of lengths of sleep were most strongly related to behavioral problems in children two and three years old but this threshold effect faded out with the four and five year olds.

The study of 510 children from two to five years old did not attempt to determine causal relationships between sleep and behavior problems, cautioned John V. Lavigne, Ph.D., who headed the seven-member team of researchers conducting the study.

Lavigne said, "The relationship between sleep and daytime behavior problems may exist because less sleep causes children to have those problems. Or because daytime behavior problems cause children to sleep less. Or because of a third variable such as the child's temperament, the parents' ability to structure sleep arrangements and daytime behavior. Or because there is some interaction effect that produces a reciprocal influence between sleep and behavior problems. There could also be a direct effect, biochemical, for example. Or a psychological mediator between sleep and daytime behavior, such as increased daytime irritability producing more tantrums."

"It's an area that is relatively unexplored, compared with what is known about young children's sleep patterns, for example," says Lavigne. "Those sleep patterns decline from an average of 13 hours per night at age two to 9.5 hours at age six."

Funding support for the study was provided by the National Institute of Mental Health.