Babies and children under the age of 5 getting less than 10 hours of sleep at night are more likely to be overweight or obese five years later, a new study suggests. Researchers found that insufficient sleep at night may be a lasting risk factor for obesity later in life and that napping cannot replace the benefits of nighttime sleep," according to a study published Monday in the journal Archives of Pediatrics & Adolescent Medicine. "This is something we may be able to change to address the growing obesity problem," said study author Dr. Janice Bell from the University of Washington. Her study analyzed data taken from a nationwide survey in 1997 and 2002. Bell found that babies and children up to age 4 who didn’t sleep enough at night were "80 percent more likely to be obese [five years later] compared to other[s] who had long sleep." However, she did not see the same link to obesity when older children (between the ages of 5 and 13) burned the midnight oil. Bell believes this is the first large, nationally representative study to suggest lack of sleep contributes to obesity in children, something that’s long been believed for adults. She says this research needs to be corroborated by other studies. The study authors also said napping is not a substitute for sleeping at night because day and nighttime sleep serve different functions. For example, naps may help reduce stress and help a child be more alert to learn, while nighttime sleep involves "complex biological, psychological and restorative functions." If children are getting less than 10 hours of sleep at night they are well below the CDC sleep recommendations, which suggest, for example, that a 1-year old baby should sleep 13-15 hours at night and 3-5 year-olds need 11-13 hours of nighttime sleep. The authors note that unlike other studies, their research did not find a difference in ethnic or social status among the children. Pediatrician Dr. Jennifer Shu said this study "gives parents one more reason to prioritize healthy sleeping habits in their young children’s lives." She said it's not entirely clear why lack of nighttime sleep contributes to weight gain, but some experts suggest that the more time a child spends awake, the more time it has to eat. Another theory suggests children who are less rested are too tired to exercise vigorously. "Regardless of the reasons involved, however, repeated studies suggest that children benefit from more sleep, not less, so parents should remember to consider sufficient sleep as part of their child's overall health and well-being," Shu said. Dr. Melina Jampolis , a physician and diet and fitness expert practicing in San Francisco and Los Angeles, also said it isn’t exactly clear why nighttime sleep is so important, but, "we know in adults that shortened sleep duration is associated with changes in substances [or hormones] like ghrelin and leptin, which can increase hunger, decrease metabolism, and lead to insulin resistance." Although she's not a pediatrician or sleep expert, Jampolis recommends some of the same suggestions for helping toddlers get to sleep as she gives to adults: Source: CNN