Sleeping just five hours a night triples the risk of excessive weight for new moms a year after a baby's birth, U.S. researchers report.

   Mothers who reported sleeping no more than five hours daily when babies were six months old had a three-times higher risk for weight retention -- at least 11 pounds -- at their baby's first birthday than moms who slept seven hours per day, the study by Kaiser Permanente and Harvard Medical School -Harvard Pilgrim Health Care said.

   The study, published in the American Journal of Epidemiology, is the first to examine sleep deprivation's impact on postpartum weight retention, a joint news release said. Previous studies examined the effect of early postpartum sleep deprivation on mothers' cognitive and emotional health.

   "We've known for some time that sleep deprivation is associated with weight gain and obesity in the general population, but this study shows that getting enough sleep -- even just two hours more -- may be as important as a healthy diet and exercise for new mothers to return to their pre-pregnancy weight," study lead author Erica P. Gunderson, Kaiser Permanente Division of Research in Oakland, Calif., said in a news release.

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