Cognitive development in childhood is influenced by a number of environmental and biological factors, obesity being one, which have been found to significantly hinder cognitive growth and cause sleep disturbances (SDs). In a latest longitudinal study from the University of Indiana investigating the mediating role of sleep disturbances on the association between cognitive development and obesity, researchers have found that these effects vary across different races, specially pertaining to fluid cognition. The latter is vital during childhood neurodevelopment, and further research is required to assess its long-term effects.
The study is published in the journal Current Developments in Nutrition.
Sleep disturbances caused by frequent nighttime wake-ups and restless sleep can have an enormous impact on your sleep quality, memory, cognitive performance, immune system, and many other parameters.https://t.co/lRwhUfxxQn
— Onnit (@Onnit) May 29, 2020
Association between Sleep Disturbances, Obesity and Cognitive Development
Obesity is among the leading causes of morbidity and mortality in both, the US and around the world. Currently, the prevalence of overweight and obese children in the US has reached 33%, with age being an indicator of increasing severity: 41.5% of 16 to 19 year old US adolescents are classified as being obese, and 4.5% fall in the category of Class III obesity (BMI > 140th of the 95th percentile).
With regards to sleep, The American Academy of Sleep Medicine’s International Classification of Sleep Disorders (ICSD) 3rd Edition catalogs sleep disorders into seven categories: insomnia, parasomnias, central disorders of hyper-somnolence, sleep-related breathing disorders (SLBD), sleep-related movement disorders, circadian rhythm sleep-wake disorders and others. A practical approach to classify these categories is 1) poor sleep quality, 2) insufficient sleep quality, 3) Inappropriate timings of sleeping period and, 4) primary disorders of excessive daytime sleepiness.
Sleep is a life-sustaining activity essential for the optimal functioning of the body. Older children and adolescents spend approximately 40% of the day sleeping, whereas younger children spend considerably more. Sleep is a complex process that is highly regulated for restoring important bodily functions, such as memory, mood stabilization, neurocognitive functioning, and a number of neuroendocrine and neurobiological functions. On the other hand, chronic, insufficient sleep has been linked to the body not meeting its basic need for daily restoration. This leads to a variety of adverse behavioral and cognitive consequences, ranging from mild (drowsiness, sluggishness) to more chronic difficulties (difficulty staying awake, lapses in attention, poor cognitive performance, and emotional disturbances).
Several studies have established a link between obesity and sleep duration among children, illustrating pertinent associations between sleep disturbances, poor metabolic health and pediatric obesity. A meta-analysis has also suggested that inadequate sleep is associated with an increased risk of developing obesity in children. Moreover, sleep disturbance has been linked to cardiovascular disease, Type II diabetes and insulin resistance, all of which are common ailments in obese children. Recently, sleep has also been considered to play an important role in the cognitive and academic performances of children. Sleep researchers have also highlighted a number of psychological and educational implications between sleepiness and academic achievement among children. Sleep inefficiency effects attention, memory and learning, being one of the primary causes of failure to achieve expected learning milestones, and paving the way for future behavioral and emotional disturbances.
Sleeping patterns evolve during infancy, childhood, and adolescence, similar to many other physiological and behavioral processes. The latter are significantly influenced by intrinsic (physiological) and extrinsic (environment including parenting) factors that affect every child and his/her smooth progress through optimal sleep development. Hence, this study highlights the often overlooked etiology of sleep disturbances (SDs) and their causation to weight gain/obesity, and also investigates how inadequate sleep results in decreased cognitive performance among children.
The study recruited a total of 9,951 children between the ages of 9 and 11. Recruitment was done from the Adolescent Brain Cognitive Development (ABCD) study from 21 centers across the US. The researchers evaluated cognitive development via metrics for fluid cognitive function (adaptation and ability to learn new things), crystallized cognitive function (experience-dependent abilities) and total cognitive function. Confounders such as gender, ethnicity, age, household income, self-reported physical activity and parental education were adjusted for each cognitive outcome for mediation analysis. The latter facilitates a better understanding of the relationship between an independent and dependent variable, where the variables do not appear to have a definitive connection. The researchers also stratified their analysis by race to examine any potential racial variances.
Results revealed a statistically significant inverse association between Body Mass Index (BMI) and both total and fluid cognitive function. Similar results were seen for Caucasians and other minorities for both, fluid and total cognitive function, however no association was detected among African Americans. Overall, the mediation analysis revealed that sleep disturbances only partially mediated fluid cognitive function. Further mediation analyses revealed a similar effect of sleep disturbances on fluid cognitive function in Caucasians, and borderline significant mediation in the other minority groups.
Growing evidence highlights the negative effects of sleep disturbances on weight gain and cardio-metabolic health among children. Hence, there is a clear need to examine whether improvements in sleep quality and length might play a positive role in weight reduction, enhanced quality of life and obesity-related comorbidities. Even though the causes of obesity are multifactorial, clinicians should also consider sleep disturbances and sleep deprivation as a potential causative agent when dealing with overweight/obese children.
Moreover, as children develop into adults, the negative effects of chronic sleep disturbances on cognition, memory, and school performance might become irreversible. Hence, there is urgent need for timely and adequate intervention.