Sleep and Obesity
by Rallie McAllister, MD, MPH
Kids who go to bed at a decent hour and then rise and shine with the sun are likely to be slimmer and more active than kids who are night owls, even when both groups they get the same amount of sleep.
These findings come from a new study* published in the journal Sleep. For the study, Australian researchers recorded the bedtimes and waking times of more than 2,000 youngsters between the ages of nine and 16. The scientists also compared their body weights and their use of free time over a four day period. Kids who went to bed late and got up late were 1.5 times more likely to be obese than youngsters who went to bed early and got up early.
The researchers also found that the night owls were less physically active than their early bird counterparts. The late-nighters were almost twice as likely to be physically inactive and they were nearly three times more likely to sit in front of the TV, computer, or Play Station playing video games for hours on end.
Remember, the kids who went to bed late and woke up late got the same total number of hours of sleep as the kids who went to bed early and woke up early. Scientists have long known that insufficient sleep can contribute to or worsen dozens of disorders and diseases, including diabetes, obesity, and heart disease. But this is one of the first studies to suggest that the timing of sleep is just as important as the amount of sleep kids get.
The researchers in this study believe that night owls are less active because mornings tend to be far more conducive to physical activity for young people than nights. Evenings offer more opportunities for TV watching, video game playing, and social networking.
Moms, you’ve got your work cut out for you. Push for an earlier bed time and encourage your kids to rise and shine with the sun. It’s more work for you, but it means better health for them.
*Tim S Olds, Carol A Maher, Lisa Matricciani. Sleep duration or bedtime? Exploring the relationship between sleep habits and weight status and activity patterns. Sleep, 2011