Does your baby sleep a lot? If not, he or she may be at risk for being overweight by preschool, says a recent Harvard Medical School study. Researchers found that the babies who slept less than 12 hours had a higher body mass index and were more likely to be overweight by the age of 3.

It’s not fully understood how sleep may influence weight, but the study’s authors hope that this will spark parents to come up ways to make their little ones get enough shut-eye. “Strategies to improve sleep duration among young children may be an important component of behavioral interventions that promote childhood overweight prevention,” they wrote. “Our findings suggest that clinicians and parents may wish to use evidence-based sleep hygiene techniques to improve sleep quality and perhaps increase sleep duration.”