As many parents know, the arrival of a baby in the house often means less sleep for Mom. Research has found a relationship between sleep patterns and obesity, heart disease, and diabetes but no one has explored whether sleep deprivation in postpartum women affects weight loss after birth. A recent study, published in the American Journal of Epidemiology, attempts to address the question of whether amount of sleep and changes in sleep patterns affect postpartum weight retention. From 1999 to 2002, the study followed 940 pregnant women from Massachusetts, starting at 22 weeks of pregnancy and continuing through the first 12 months after birth. During interviews conducted in early pregnancy and at six months postpartum, the women responded to questions about their sleep patterns and infant feeding practices. At one year, additional information was collected by mail-in questionnaires. In their analysis, the researchers looked at the link between number of hours of sleep per 24 hour period  6 months after delivery and failure to return to one’s pre-pregnancy weight  (that is, retaining at least 12 or more lb at one year after giving birth). Getting five or less hours of sleep over a 24-hour period doubled the risk of substantial weight retention at one year postpartum. Even greater risk of weight retention was found among those mothers who continued to lose sleep (i.e. actually decreased amount of sleep time) between 6 and 12 months.  So new mothers, take a nap!