March 19, 2019
2 min read

Cortisol may not be implicated in link between childhood BMI, sleep duration

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Short sleep duration is associated with increased BMI, but connections with cortisol production seen in adults are not apparent in children, according to findings published in Obesity.

“The mechanisms that link short sleep duration and BMI during childhood are not well understood,” Kristine Marceau, PhD, assistant professor in the department of human development and family studies at Purdue University in West Lafayette, Indiana, and colleagues wrote. “Research conducted with adults has suggested several paths, including the impact of short sleep duration on the regulation of hormones related to hunger and satiation (ie, ghrelin and leptin) and hypothalamic-pituitary-adrenocortical (HPA) axis functioning. ... The current study focuses on HPA dysregulation as a potential explanatory mechanism for associations between short sleep duration and BMI across childhood.”

Marceau and colleagues conducted a cross-lagged panel model, with modeled random intercepts that used data from cohort I of the Early Growth and Development Study. A total of 316 children (57% boys) and their families from adoption agencies in 10 U.S. states were included in the analysis. Measures of cortisol levels, sleep duration, weight and height were collected at age 4.5, 6, 7 and 9 years. Cortisol levels were assessed via saliva samples at age 4.5, 6 and 7 years. Sleep duration was reported by a participant’s parents, and height and weight, which were used to calculate BMI, were reported by the parent or in medical records at age 4.5, 6, 7 and 9 years.

The researchers found that children with higher BMI at age 6 years generally had longer sleep times from age 6 to 7 years. Meanwhile, BMI was higher from age 7 to 9 years when morning cortisol levels were lower, and lower cortisol levels at night at age 7 years were predicted by elevated BMI at age 6 years. Taken together, the researchers wrote that the primary findings of the study were that cortisol levels fluctuated while sleep duration did not, but that any association between BMI and sleep duration was not explained by cortisol levels.

“Contrary to our expectations, HPA activity did not mediate associations between sleep duration and BMI across childhood,” the researchers wrote. “However, we found evidence of time-specific associations between low cortisol levels and higher BMI. These latter findings suggest an emergent association between low cortisol and child BMI during middle childhood that may parallel recent research on BMI change and lower cortisol levels in adults.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.