Promoting longer, more regular sleep, even catching up at weekends on sleep lost in the week, may help reduce the incidence of childhood obesity, concluded US researchers in a new study published online in a leading journal this week.

You can read how Dr David Gozal, Professor and Chair of the Department of Pediatrics at the University of Chicago Medical Center, Chicago, Illinois, and colleagues, arrived at this conclusion in a paper published online on 24 January in the journal Pediatrics.

Previous studies have already reported that insufficient sleep is linked to an increased risk of obesity in children, but in this study, Gozal and colleagues set out specifically to explore the effect of duration and regularity of sleep on BMI and metabolic regulation in children.

BMI stands for Body Mass Index, a measure of obesity, expressed in kg per meter squared, and equal to a person’s weight divided by the square of their height.

For this cross-sectional study, they recruited 308 community-resident children aged 4 to 10 years, and measured their BMIs, their blood glucose before eating in the morning, insulin, blood fats and cholesterol. In a sub-sample group, they also measured levels of high-sensitivity C-reactive protein (an “inflammation” marker used to assess risk of cardiovascular disease).

The children wore wrist monitors for a week. These measured physical activity and allowed the researchers to assess how often, when the children slept, and how long for, over the week.

The results showed that:

  • The children slept for 8 hours every night on average, regardless of their BMI.
  • However, there was also a non-linear trend between sleep and weight.
  • The children in the obese BMI range, slept fewer hours and showed greater variability in the differences between weekend sleep time and school days sleep time.
  • Children whose BMI was in the overweight range, showed an inconsistent sleep pattern.
  • Analysis of sleep patterns and blood markers showed that high variance in sleep duration, or shorter sleep duration, was more likely to be linked to altered levels of insulin, LDL cholesterol, and high-sensitivity C-reactive protein.
  • Children who slept the least, particularly those who also had irregular sleep patterns, showed the greatest health risk (ie the riskiest combination of BMI and blood markers).

The researchers found that just an extra half hour of sleep every night was linked to lower BMI and reduced pattern of risky blood markers.

And they also found that catching up with sleep at the weekend was linked to a lower risk of obesity, they wrote that:

“Obese children were less likely to experience ‘catch-up’ sleep on weekends, and the combination of shorter sleep duration and more-variable sleep patterns was associated with adverse metabolic outcomes.”

They concluded that:

“Educational campaigns, aimed at families, regarding longer and more-regular sleep may promote decreases in obesity rates and may improve metabolic dysfunction trends in school-aged children.”

“Sleep Duration, Sleep Regularity, Body Weight, and Metabolic Homeostasis in School-aged Children.”
Karen Spruyt, Dennis L. Molfese, David Gozal.
Pediatrics, Published online 24 January 2011

Additional source: Cleveland Clinic (online health information services).

Written by: Catharine Paddock, PhD