Turns out Benjamin Franklin was right. His beloved adage: "Early to bed, early to rise, makes a man healthy, wealthy and wise" took on new meaning recently, with the publication of a study by Australian researchers, which concluded that children who go to bed early, and rise early, are less likely to be obese than their night-owl peers.

Surprisingly, the effect had nothing to do with the relative amounts of shut-eye kids were getting. According to the study, published in the Oct. 1 issue of the journal SLEEP, time spent sleeping was about equal between early-to-bed and late-to-bed kids.

But investigators identified one important difference between the two groups, comprised of more than 2,000 pre-teens and adolescents from across Australia; kids who went to bed later and rose later also spent, on average, 48 more minutes longer sitting in front of a screen; online, watching TV or playing video games. On the flip side, their early-to-bed peers spent, on average 27 more minutes of their waking time being active each day.

The implication is clear; when a kid goes to sleep, and how he spends his free time has an impact on general health. Early birds were leaner, and more physically active than their night-owl peers according the study.

"The children who went to bed late and woke up late, and the children who went to bed early and woke up early got virtually the same amount of sleep in total," said co-author Carol Maher, PhD, a postdoctoral fellow with the University of South Australia.

"Scientists have realized in recent years that children who get less sleep tend to do worse on a variety of health outcomes, including the risk of being overweight and obese. Our study suggests that the timing of sleep is even more important."

Roughly speaking, kids who turned in early got about 30 minutes more moderate to vigorous activity each day than kids with later bedtimes. And that appears to make a surprisingly big difference. Body mass index (BMI) scores were higher among late-to-bed kids, and they were more likely to be

overweight or obese, than their peers who turned in earlier.

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