A new study suggests that it is the rate of change in sleep problems across development, rather than the initial level of sleep problems, that may affect cognitive abilities in late adolescence.
Results indicate that those children whose sleep problems persisted across development had poorer executive functioning at age 17 than children whose problems decreased to a greater extent. Sleep problems declined across the years of childhood development, with approximately 70 percent of children having more than one problem at age 4 and about 33 percent of children having problems at age 16.
Sleep problems as early as age 9, but particularly around age 13, showed significant associations with later executive functions. The findings suggest that a child's level of sleep problems early in life, when such problems as nightmares and trouble sleeping may seem more common, do not appear to have appreciable implications for eventual executive control.
The study considered seven specific sleep problems: nightmares, sleep talking, sleepwalking, bedwetting, sleeping less or more than most children during the day or night, trouble sleeping and being overtired. According to principal investigator and lead author Naomi Friedman, PhD, senior research associate at the Institute for Behavioral Genetics at the University of Colorado at Boulder, the results also show that certain sleep problems in children may affect later executive functioning more than others.
"When we looked at each of the seven sleep problems separately, we found that changes in levels of 'sleeping more than other children' and 'being overtired' were the strongest predictors of later executive control, and developmental trajectories of nightmares and 'trouble sleeping' were the weakest predictors," said Friedman.
According to the authors, executive functions are cognitive-control mechanisms that help regulate thoughts and actions. The study evaluated three executive functions: "inhibiting" - the ability to stop a dominant or automatic response; "updating" - the ability to continuously update the contents of working memory by adding new relevant information and deleting older irrelevant information; and "shifting" – the ability to rapidly shift between two tasks.
Longitudinal data were collected on parent-reported sleep problems for 916 twins (465 female, 451 male). Parents reported their children's sleep problems at ages 4, 5, and 7 years, and then each year from ages 9 through 16 years. Sleep problems were based on seven questions of the Child-Behavior Checklist.
A subset of 568 of the children completed laboratory assessments of executive functioning at age 17. Participants completed three computerized tasks for each executive function.
The authors note that an association of sleep problems with executive functioning may be particularly important since executive functions are considered key mechanisms in many models of cognitive development and disorders such as attention-deficit/hyperactivity disorder (ADHD), substance abuse problems, mood problems and more general problems of externalizing behavior. Many of these disorders are also associated with sleep loss and other sleep problems.
According to the authors, these findings emphasize the importance of early recognition and treatment of persistent sleep problems in childhood and adolescence. In particular, parents should be aware of their child's patterns of sleepwalking, sleep talking, being overtired or sleeping more than others. There is evidence that recognizing and addressing sleep problems early may reduce any negative impact on executive control.
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