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Inadequate sleep elevates risk of childhood obesity--study

Though the link between sleep and weight gain is ambiguous, researchers theorize sleep shortfalls leads to drowsiness, less physical activity due to tiredness and burning of fewer calories.

Something as simple as helping kids sleep more at night could be the key to tackling the obesity epidemic among children.

Earlier studies have established that inadequate sleep can have a negative impact on a child's social and emotional well-being and school performance.

Now, a new study finds that lack of nighttime sleep in infants and toddlers also increased their risk of being overweight.

Co-author of the study, Frederick Zimmerman, a researcher at the University of California Los Angeles (UCLA) stated, “These findings suggest that there is a critical window prior to age five years when night-time sleep may be important for subsequent obesity status.

"Sleep duration is a modifiable risk factor with potentially important implications for obesity prevention and treatment.

"Insufficient nighttime sleep among infants and preschool-aged children appears to be a lasting risk factor for subsequent obesity, while contemporaneous sleep appears to be important to weight status in adolescents.”

Link between sleep and overweight status assessed
In a bid to assess the relationship between sleep and overweight status, the researchers analyzed data of 1,930 children at the start of the study in 1997 and then again followed it up in 2002.

The children were divided into two groups. The first comprised the “younger” (aged 1 to 59 months) and the second “older” (age 5 to 13 years).

Overweight was defined as being at or above the 85th percentile of national growth standards and obesity was defined as being at or above the 95th percentile.

The researchers used time diaries, in which the parents or caregivers of young children recorded all their activities, including bedtime, time asleep and wake time during a typical day.

They also assessed other information known to influence childhood obesity such as parents' weight and the child's physical activity level and whether they napped during the day.

The study found that napping by the young kids during the day appeared to have no effect on their weight. Among the older children, inadequate sleep at night indicated an increased risk of a shift from normal weight to overweight and from overweight to obesity.

Revelations of the study
It was noted that at an average, the younger kids in the study slept 10 hours a night while those older slept around 9.5 hours. However, there were some children in both groups who got as little as five hours' sleep a night.

The analysis of the diaries indicated a troubling age-related trend in sleep behavior.

After a five year follow-up, 33 percent of the younger children and 36 percent of the older children were overweight or obese.

The study found that napping by the young kids during the day appeared to have no effect on their weight. Among the older children, inadequate sleep at night indicated an increased risk of a shift from normal weight to overweight and from overweight to obesity.

The researchers stated, "For the younger children, low nighttime sleep at baseline was significantly associated with increased odds of overweight versus normal weight and increased odds of obesity versus overweight at follow-up.”

Some plausible explanations
Though the link between sleep and weight is ambiguous, researchers theorize sleep shortfalls leads to drowsiness, less physical activity due to tiredness and burning of fewer calories.

In addition, more time awake means more time to eat calorie-rich snacks during the day.

Experts believe a lack of sleep causes an imbalance in certain hormones that control appetite, hunger and metabolism.

The study appears in the September issue of the 'Archives of Pediatrics & Adolescent Medicine.'