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 Behavior, offers insight into how a child’s socioeconomic environment might alter their neural development.
“Socioeconomic disadvantage is prevalent in the United States and worldwide 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 unfold are not well understood. We conduct research that uncovers these pathways.”
“Socioeconomic disadvantage is a distal environmental factor that often impacts multiple aspects of children’s immediate environments, including by increasing their stress. Sleep is critically important to children’s development, and stress is known to interfere with sleep quality and quantity.”
“We believe that socioeconomic disadvantage may impact children’s sleep, leading to differences in their brain development, and that these effects may partially explain socioeconomic disparities in children’s cognitive outcomes.”
The researchers used flyers and local community events in New York to recruit a socioeconomically diverse sample of 94 parents and their 5- to 9-year-old children.
The participants first visited the lab and completed assessments regarding socioeconomic factors, such as family income, parental education, and the number of people in the household. The parents then completed questionnaires regarding their child’s sleep durations, sleep environment, and family routines. Roughly one month later, the children participated in an structural brain scanning session.
The researchers found that lower parental education and lower family income-to-needs ratio (indicating greater socioeconomic disadvantage) were significantly associated with shorter weekday sleep duration in children. Shorter weekday sleep duration, in turn, was associated with smaller amygdala volume and reduced cortical thickness in several brain regions, including the left middle temporal, right postcentral, and right superior frontal cortices.
“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 impacts these outcomes in children in part through its effects on their sleep duration.”
“Ensuring that all children have opportunities for healthy development is crucial. Supporting children’s sleep may be one way to cultivate healthy brain development. Insufficient sleep is disproportionately found among children in socioeconomically disadvantaged environments. Therefore, addressing barriers to healthy sleep in these contexts is particularly important and may support brain development.”
The researchers also found evidence that less frequent family routines partially explained the relationship between socioeconomic disadvantage and weekday sleep duration in children. Those with less frequent family routines disagreed with statements such as “Children do the same things every morning as soon as they wake up” and “Family has certain ‘family time’ each week when they do things together at home.”
However, Merz noted that “our study is not equipped to infer causal effects, and there are many research questions that still need to be addressed. An important next step is identifying the types of prevention or intervention strategies that are effective in terms of improving sleep in children in socioeconomically disadvantaged environments.”
The study, “Socioeconomic disparities 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.