CHOP researchers study impact of developmental sleep patterns on bone density

Researchers at the Children’s Hospital of Philadelphia are studying how sleep patterns during children's developmental ages can impact bone density and strength as an adult. 

Dr. Jonathan Mitchell, an assistant Pediatrics professor at the Perelman School of Medicine, is leading the study, which is funded by a new grant from the Eunice Kennedy Shriver National Institute of Child Health & Human Development. 

While existing research shows that amount of sleep is linked to bone density in adults and animal models, there is little research that sleep has a similar effect on children. Mitchell said it is essential to remember that bone growth primarily occurs during childhood and early adulthood, so it is important to determine if the risk of osteoporosis and potential bone fractures could be minimized with better sleep. 

“There are so many factors [associated with sleep] like physical growth, cognitive growth, and development, and that will hopefully translate into pediatricians ensuring that sleep behavior is prioritized as kids are developing,” Mitchell said. 

A preliminary version of the study was conducted over the past five years with early results showing an inverted U-shaped association with sleep patterns and bone health, meaning that participants who slept longer or shorter were found to have lower bone mineral density and lower bone strength, according to CHOP's Cornerstone Blog. 

The CHOP researchers' current project expands upon this earlier study by measuring sleep more robustly and for a longer period of time. 

The researchers will use dual-energy x-ray scans and three-dimensional tomography processes to evaluate bone density and determine bone strength. The study will enroll students between the ages of 12 and 13 who are generally healthy and receive primary care at CHOP. In addition to undergoing scans, students will also wear actigraphy devices to measure their sleep patterns, including movement. 

Although the study was delayed by the COVID-19 pandemic, it is now prepared to enroll the first cohort of children at the start of the upcoming school year. 

Mitchell said he and his research team had to modify parts of the study to account for environmental changes children have faced due to the pandemic, including adding survey questions to better understand their behavior and considering the potential impact on sleep patterns if students do not return to school in person this fall.

“If schools are closed because of COVID-19, we could see dramatic changes in their sleep timing and therefore sleep duration, so it’ll be really fascinating,” Dr. Mitchell said. “We need shorter sleepers, longer sleepers, early-to-bed kids, later-to-bed kids, etc. We definitely need variation to control these things to determine if there’s an association.”