Brain imaging study links socioeconomic differences in children’s sleep to reduced cortical thickness

A new study has found that children from disadvantaged families tend to sleep less, and that this lack of sleep is linked to reduced cortical thickness in areas related to language, self-control and movement.

Cortical thickness refers to the measurement of the thickness of the cerebral cortex, the outermost layer of the brain. It is often used as an indicator of brain development and maturation, and can be measured using imaging techniques such as magnetic resonance imaging (MRI).

The new findings, published in Brain and behaviorprovides insight into how a child’s socioeconomic environment can alter their neural development.

“Socioeconomic disadvantage is widespread in the United States and around the world and known to interfere with children’s cognitive development,” said study author Emily C. Merz, an assistant professor at Colorado State University and principal investigator of the Learn Lab.

“Accumulating evidence suggests that socioeconomic differences in brain structure underlie these effects on cognitive development. Yet the pathways through which these effects play out are not well understood. We are conducting research that uncovers these pathways.”

“Socioeconomic disadvantage is a distal environmental factor that often affects multiple aspects of children’s immediate environment, including by increasing their stress. Sleep is critically important to children’s development, and stress is known to disrupt sleep quality and quantity.”

“We believe that socio-economic disadvantage can affect children’s sleep, lead to differences in brain development, and that these effects can partly explain socio-economic differences in children’s cognitive outcomes.”

The researchers used flyers and community events in New York to recruit a socioeconomically diverse sample of 94 parents and their 5- to 9-year-old children.

Participants first visited the laboratory and completed assessments regarding socioeconomic factors, such as family income, parental education, and number of people in the household. The parents then filled in questionnaires regarding the child’s sleep duration, sleep environment and family routines. About a month later, the children participated in a structural brain scan.

The researchers found that lower parental education and lower family income in relation to needs (indicating greater socio-economic disadvantage) were significantly associated with shorter weekday sleep in children. Shorter sleep duration on weekdays was in turn associated with smaller amygdala volume and reduced cortical thickness in several brain regions, including left middle temporal, right postcentral and right superior frontal cortex.

“Shorter weekday sleep duration was associated with reduced gray matter in parts of the brain important for self-control, language and somatosensory processing,” Merz told PsyPost. “It is possible that socioeconomic disadvantage influences these outcomes in children in part through its effects on sleep duration.”

“Ensuring that all children have opportunities for healthy development is essential. Supporting children’s sleep can be a way to cultivate healthy brain development. Inadequate sleep is disproportionately found among children in socio-economically disadvantaged environments. Therefore, it is particularly important to address barriers to healthy sleep in these contexts and can support brain development.”

The researchers also found evidence that less frequent family routines partially explained the link between socioeconomic disadvantage and sleep duration in children on weekdays. Those with less frequent family routines disagree with statements such as “Kids do the same things every morning as soon as they wake up” and “The family has some ‘family time’ every week when they do things together at home.”

Merz noted, however, that “our study is not powered to infer causal effects, and there are many research questions that remain to be addressed. An important next step is to identify the types of prevention or intervention strategies that are effective in improving sleep in children in socio-economically disadvantaged environments.”

The study, “Socioeconomic Differences in Sleep Duration Are Associated with Cortical Thickness in Children,” was authored by Melissa Hansen, Katrina R. Simon, Jordan Strack, Xiaofu He, Kimberly G. Noble, and Emily C. Merz.

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