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Children who sleep less are more likely to be overweight

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A LACK of sleep is more likely to lead to overweight children than a poor diet or lethargic lifestyle, a new long-term study has found.

This study was released today. The cause of children being overweight is often put down to eating too much and exercising too little. However in this study, three factors – activity, food intake and hours of sleep, were measured –  and lack of sleep had the greatest link to risk of obesity.

Are we underestimating the effect lack of sleep has on our children? I think we are are. I have written about the effect of lack of sleep on children’s behaviour and academic ability previously here: Want to make your children smarter by two years? Put them to bed earlier.

If you are a parent – are your children getting enough sleep? In our family this is one area of our children’s life that we are strict on. We have the following rules in our house; we garnered these tips from a number of places so that our children get a good nights sleep. Of course there are the occasional late nights, but rarely on a school night.

  • No computer or TV, Ipod etc. at least 1 hour before bedtime (and absolutely NO TVs, computers or other interactive gadgets in the bedroom)
  • No cellphones in the bedroom at nightime.
  • Strict enforcement of bedtime, failure to get to bed on time means a reduction in screen time the next day.
  • Homework can get in the way of getting to bed on time, so we help our kids by getting rid of the distractions. 45 minutes of fun computer time on school nights, monitored by Kidswatch. No TV on school nights. No TV other nights before 5pm and none after 8.00pm. No TV on Sunday evening until homework is completed.

Our children are now almost 13 and 15, and these rules are just part of their life. Do they complain and tell us other kids have it better? Of course. But this study shows that teens consistently overestimated the actual levels of their peers’ autonomy, assuming that others had more freedoms than they did. So when your kids tell you their lives are way more restricted than their peers – they are probably wrong.

And a tip for those who have young children, and wake up at the crack of dawn then insist on waking the rest of the house. We found this worked – get them a clock, teach them how to read one time only – 7.00am. Our rule was that our kids were not to make any noise or wake anyone up before 7. They could play quietly if they wanted to. It worked for us. Our children were able to do this from 3 years old.

With regards to this New Zealand Study Professor Taylor, a pediatrician and academic from the Dunedin School of Medicine, (in this article) made the following comments:

“… how active you are actually seems to have no effect on whether or not you’re overweight at the age of seven,” he told AAP.

“The food that you ate had some effect, but actually the biggest effect was short sleep.”

He said the children slept an average of 11 hours each night and those that got any less shut-eye were more likely to be overweight, even if other factors were controlled.

“It’s a complicated connection,” said Prof Taylor.

He said the amount of sleep a person got altered the hormones controlling metabolism and appetite, hence, how much one eats.

“We were surprised by how big a factor (sleep was),” Prof Taylor said.

“I was expecting the … percentage of food eaten as vegetables and fruit would be more important and that activity levels … would be more important.”

Evidence suggests the amount of sleep both children and adults get has dropped significantly in the past 30 years, Prof Taylor said, blaming a “modern lifestyle”.

Children Who Sleep Less Are More Likely to Be Overweight, Study Finds

ScienceDaily (May 26, 2011) — Young children who do not get enough sleep are at increased risk of becoming overweight, even after taking account of lifestyle factors, finds a study published online in the British Medical Journal.

Several studies have shown a relatively consistent relation between shorter sleep duration and increased body weight in children, but doctors are still not sure how sleep and body composition interact in early childhood and whether this shows cause and effect.

So a team of researchers in New Zealand set out to investigate whether reduced sleep is associated with differences in body composition and the risk of becoming overweight in young children.

They identified 244 children who were taking part in The Family Lifestyle, Activity, Movement and Eating (FLAME) study in Dunedin, New Zealand.

Each child’s weight, height, body mass index (BMI), and body composition were measured every six months from 3 to 7 years of age. Sleep habits and physical activity levels were assessed by accelerometry (the children wore a belt carrying a device that monitors body movement) and dietary intake by questionnaire at 3, 4 and 5 years.

Other factors, such as birth weight, mothers’ education, income, BMI, smoking during pregnancy and ethnicity were also recorded because of known links with BMI in children.

Average sleep duration was about 11 hours per day at all three ages.

The results show that young children who sleep less are at a significantly increased risk of having a higher BMI by age 7, even after controlling for other risk factors that have been implicated in body weight regulation.

Each additional hour of sleep per night at age 3 to 5 years was associated with a reduction in BMI of 0.49 and a 61% reduction in the risk of being overweight or obese at age 7.

In a child of average height, this corresponds to a difference of 0.7kg body weight. While this might seem minor at an individual level, the benefits for public health, if applied at the population level, are considerable, say the authors.

More importantly perhaps, the reductions in BMI were due to differences in fat mass, rather than any effect on fat-free mass, showing that poor sleep has negative effects on body composition.

Note: Lack of sleep has also been shown to have a negative effect on body composition of adults. Lack of sleep when on a diet causes more muscle loss, less fat loss, increases hunger hormone.

They suggest that reduced sleep may increase dietary intake and may also influence energy expenditure, leading to reduced exercise.

In conclusion, it appears that sleep is an important determinant of future body composition in young children, say the authors. They recommend that appropriate sleep habits should be encouraged in all children as a public health measure, and call for more studies to determine whether more sleep or better sleeping patterns impact favourably on body weight and other health outcomes.

This view is supported in an accompanying editorial by Professor Francesco Cappuccio and Associate Professor Michelle Miller from the University of Warwick. They say that, not only may prolonged lack of sleep be a direct contributor of overweight and obesity in children, it could also have other effects on long term health.

They call for future research to explore new behavioural methods to prolong children and adults’ sleeping time, and suggest that, in the meantime, it would do no harm to advise the general public of all ages that a sustained curtailment of sleeping time might contribute to long term ill-health in both adults and children.

Journal Reference:

P. J. Carter, B. J. Taylor, S. M. Williams, R. W. Taylor. Longitudinal analysis of sleep in relation to BMI and body fat in children: the FLAME study. BMJ, 2011; 342 (may26 2): d2712 DOI: 10.1136/bmj.d2712

This recent study too found that obese and overweight older children lacked sleep. For children who do not sleep enough during the week – weekend catchup sleep is particularly important.

Sleep duration, sleep regularity, body weight, and metabolic homeostasis in school-aged children.

OBJECTIVE:

The goal was to explore the effects of duration and regularity of sleep schedules on BMI and the impact on metabolic regulation in children.

METHODS:

Sleep patterns of 308 community-recruited children 4 to 10 years of age were assessed with wrist actigraphs for 1 week in a cross-sectional study, along with BMI assessment. Fasting morning plasma levels of glucose, insulin, lipids, and high-sensitivity C-reactive protein also were measured for a subsample.

RESULTS:

Children slept 8 hours per night, on average, regardless of their weight categorization. A nonlinear trend between sleep and weight emerged. For obese children, sleep duration was shorter and showed more variability on weekends, compared with school days. For overweight children, a mixed sleep pattern emerged. The presence of high variance in sleep duration or short sleep duration was more likely associated with altered insulin, low-density lipoprotein, and high-sensitivity C-reactive protein plasma levels. Children whose sleep patterns were at the lower end of sleep duration, particularly in the presence of irregular sleep schedules, exhibited the greatest health risk.

CONCLUSIONS:

Obese children were less likely to experience “catch-up” sleep on weekends, and the combination of shorter sleep duration and more-variable sleep patterns was associated with adverse metabolic outcomes. Educational campaigns, aimed at families, regarding longer and more-regular sleep may promote decreases in obesity rates and may improve metabolic dysfunction trends in school-aged children.

Spruyt K, Molfese DL, Gozal D Sleep duration, sleep regularity, body weight, and metabolic homeostasis in school-aged children.
Pediatrics. 2011 Feb;127(2):e345-52. Epub 2011 Jan 24.

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