Theory No. 299 on why children are getting so plump these days: They go to bed too late. So suggests a team led by Jim Dollman of the University of South Australia.

In case anyone was not aware by now, children and adults are fatter than they used to be. (This has been covered some in the news.) The go-to-bed-too-late theory, published online in the journal Acta Paediatrica, stems from a comparison of the habits of Australian kids in two surveys, conducted in 1985 and in 2004. In both, Aussie youth ranging in age from 10 to 15 years were asked (among other things) what time they went to bed.

A comparison of the two surveys revealed that kids now go to bed, on average, at about 10:15 p.m. That is half an hour later than in 1985.


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Interestingly, children have been getting fatter during just that period.

It may sound nutty to propose such a link — though, of course, one can stuff a heck of a lot of Ruffles and ice cream down a gullet in 30 minutes if one sets one's mind to it — but there are some studies, too, suggesting plumper adults get less sleep. Scientists have proposed that sleep deprivation ramps up the appetite by messing with levels of two hormones, leptin and grehlin.

Read about that strand of research here: www.webmd.com/diet/news/20041116/sleep-more-to-fight-obesity.

And to listen to audio of an interview with Dollman, go to abc.net.au/news/items/200705/1935939.htm?sa.

— Rosie Mestel