Less sleep linked to childhood obesity

Spruyt K. Pediatrics. 2011;127:e345-e352.

Issue: February 2011

Obese children are more likely to fall short on sleep, have more variable sleep patterns and, subsequently, develop harmful metabolic profiles compared with normal-weight and overweight children, recent data suggest.

To investigate the effect of sleep on weight in the pediatric population, researchers measured BMI and recorded the total sleep time for 308 children aged 4 to 10 years. They also gauged metabolic changes by examining plasma glucose levels, insulin, lipids and high-sensitivity C-reactive protein (hs-CRP) in 36.6% of the cohort.

On average, children in all weight groups slept 8 hours per night, regardless of whether it was a school night or weekend night. Obese children, however, experienced more variable total sleep time on weekends vs. school days, with shorter sleep duration on weekends. In comparison, normal-weight and overweight children maintained relatively steady sleep patterns throughout the entire week, although normal-weight children generally slept longer or received “catch-up sleep” on weekends.

Results further revealed that sleep duration shortened as the week progressed for obese children, reaching the lowest point during weekends. Conversely, overweight children extended their sleep duration throughout the week and into the weekend. Friday nights represented the starkest contrast in sleep patterns between obese and overweight children, the researchers said.

Adversely altered insulin, LDL and hs-CRP plasma levels emerged among children who had shorter sleep duration and highly variable sleep patterns compared with other children, according to the researchers. They also appeared to be at higher risk for eventually developing these health problems.

“Considering the reported trends indicating that children sleep progressively less, an alarming aspect is that, when children are given the opportunity to sleep, they tend to sleep more, as observed on weekends and holidays, and such compensatory sleep seems to mitigate some of the adverse effects on weekday sleep patterns,” the researchers wrote. “These observations prompt questions regarding the interrelationships of lifestyle-modified sleep and the obesity epidemic.”

The researchers noted, however, that educational public health campaigns advocating more sleep may help improve this issue.

Disclosure: The researchers report no relevant financial disclosures.

Every pediatrician is concerned about the epidemic of childhood obesity. Sleep difficulties across the age spectrum in pediatrics occupy a relatively small but significant amount of time in our daily office visits. Unfortunately, we truly know little about either problem. The good news is that on both fronts, current research is adding 'weight' to preliminary hypotheses that have been generated over the past decade. Obesity is a disease and we need to understand its pathophysiology in order to prevent it as well as target therapy. The rapid increase in prevalence of obesity over a relative short time span argues that the root cause reflects environmental effects on a susceptible (genetic) population. Of the many environmental effects that could be at play, sleep certainly seems to be one that needs our attention. Previous research has associated sleep deprivation with hyperphagia and sleep curtailment with decreased leptin and increased ghrelin levels, which mediate increased hunger and appetite. Sleep also appears to play a role in energy homeostasis.

The current study looks at sleep duration, sleep regularity, BMI and metabolic homeostasis in school-aged children. In this community-based study of children aged 4 to 10 years, researchers found that children routinely slept only 8 hours a night, although the National Sleep Foundation suggests that 10 to 11 hours are needed, across all weight categories including normal weight. Obese children were found to be less likely to have 'catch-up' sleep on weekends, and the combination of shorter sleep duration and more variable sleep patterns was associated with adverse metabolic outcomes. The longer and more stable sleep duration was, the less likely the child was to manifest metabolic dysfunction. The study has limitations based on short period of assessments (7 days); metabolic samples being done on only a representative subsample of the study population; BMI measurement being the sole determinant of obesity without other ascertainment of body fat distribution; and a study population of predominately white non-Hispanic children. Importantly, the study design cannot determine causality.

However, as we further tease apart the pathophysiology of obesity, follow-up studies can now be designed to further explore the interaction of sleep and obesity. In the meantime, it makes sense on many levels to pursue the authors' suggestions to educate families regarding the benefits of longer and more regular sleep on obesity and its associated metabolic dysfunction.

– William T. Gerson, MD
University of Vermont South Burlington, VT

Disclosure: Dr. Gerson reports no relevant financial disclosures.

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