Babies aged between six months to three years who do not get enough sleep at night could be at a greater risk of later childhood obesity, a new study suggests.

The researchers found that naps during the day might not be adequate relief for sleep lost during the nights and babies who stayed awake at night were more likely to get obese in their later years.

The study report, published in the latest issue of the Archives of Pediatrics & Adolescent Medicine, suggests that there is a critical time period before the age of five years when night sleep could be crucial for subsequent obesity status. Co-authors Janice F. Bell of the University of Washington in Seattle, and Frederick J. Zimmerman of the University of California, Los Angeles felt that sleep duration among babies was a modifiable risk factor.

The study collected data from more than 1,930 children across the United States in the one to 13 year age-group. These kids were divided into two groups with the younger ones aged between one an five years clubbed together and the older children forming another group. The researchers collected data from the entire group when the study began in 1997 and once again in 2002 as a follow-up process.

After the second round of data collection, it was observed that 33 percent of the younger children and 36 percent of the older ones were obese or overweight. Among the younger kids, the lack of sufficient nighttime sleep was noted as the basic factor for the obesity symptoms in later years.

Among the older kids, the amount of sleep at the baseline was not associated with the weight during the follow-up interaction, but the researchers found that a lack of nighttime sleep was indeed linked to increased risk of a shift from normal weight to overweight.

The authors said the latest study proves that sleep duration was a modifiable risk factor with potentially important implications for obesity prevention and treatment. And insufficient nighttime sleep among babies could become a lasting risk factor for subsequent obesity.