Is lack of sleep making kids fat?

Along with the usual culprits like inactivity, fast food and junk food ads, here comes another to add to the list of factors in childhood obesity - going to bed late. Sleep deprived children and teenagers are more likely to be overweight say the results of a new US study published in the journal Child Development.

The findings add to growing evidence that going to bed too late - or getting up too early - may be contributing to weight gain. When you're chronically shortchanged of sleep, say some scientists, up go levels of your 'hunger hormone', a hormone called grehlin that boosts appetite (especially for sugary foods), and down go levels of leptin, the hormone that tells you when you've had enough to eat. As for what's keeping kids up late, say sleep experts, it's, well, Life - a complex mix of too little time and too much technology, along with a lack of awareness among many parents of how much sleep children need

When I interviewed Adelaide sleep researcher Sarah Blunden for the Sydney Morning Herald last year she said that 90 per cent of parents she sees in her sleep psychology practice don't set limits about bedtime, either because they don't realise how much sleep children need - or because the child doesn't want to go to bed.

A study of five to 12-year-old children and sleep by Dr Blunden, the adjunct research fellow at he University of South Australia's Centre for Sleep Research, found that 40 per cent of them had sleep problems related to factors like anxiety, having a TV or computer in the bedroom, not having a quiet wind down period before bed - or having parents who don't lay down rules.

"I'm having trouble getting my son to sleep," a neighbour with a seven- year-old told me not long ago. Then she paused and said, "Do you think it's because he has a TV in his room?"

But while late nights might sound like a job for Super Nanny, it's not just about setting limits and keeping TV out of bedrooms. The same things that keep kids up late are often the same obstacles that can get in the way of eating healthy - too many competing demands on our time .

Many working parents say there's so much to do when they get home that bedtime gets pushed back later. Sometimes bedtimes are delayed so that kids can spend time with fathers whose own working hours mean they get home late. As for TV's influence, it's not just food ads or the fact that it keeps kids awake - there once was a time when kids would wear themselves out, not in front of a screen, but running around outside.

As for what's a healthy amount of sleep for kids, Dr Chris Seton of the Children's Hospital in Westmead in Sydney suggests:
-Pre-schoolers: 12 hours sleep in a 24 hour period
-Primary school children: 9-10 hours
-12 - 17-year-olds: 9 - 10 hours

The rules for helping kids get to sleep earlier aren't rocket science - no caffeinated drinks including cola or energy drinks for at least four hours before bed, a wind down period of half an hour to an hour before bed - preferably without TV - and keeping TVs, computers, play stations and mobiles out of bedrooms.

But how easy are they to implement in 2007? While coaxing a five-year-old under the doona is one thing, prising a 15 year old away from a mobile is another...