Reuters has an article about obesity that contained an interesting nugget or two:

More than eight hours' TV a week or less than 10-1/2 hours' sleep a night for a three-year-old increase the risk of piling on the pounds, [experts say.

No doubt that the sedentary nature of watching TV can lead to weight gain. I'm less certain what the connection to sleep is, though I'm sure a case can be made that the multitude of problems that lack of sleep causes would include metabolism.

But I can't help but wonder if there is another factor at work here. Rather than being simply cause-and-effect, they could just be associative conditions of something else entirely: overly permissive or disinterested/busy parents.

I'd imagine that permissiveness is a pretty big factor in childhood obesity today. I think that today parents face a certain guilt that wasn't as prevalent in previous generations because of the dual-income household. The lack of time would also contribute to parents not having the time and energy to monitor their childrens habits, whether it be sleep, television, or diet. And, of course, it's no secret that television is the second best babysitter that there is after our public school system. And I'd imagine for some parents, letting your kid stay up in his or her room is less trouble than checking in on them and having inevitable arguments about going to bed.

It's possible the study controlled for that comparing siblings, though there's no indication that it did.