VOA常速英语:Babies' Growth Spurts Tied to Longer Periods of Sleep

New research confirms what many grandparents already know: Infants wake up taller right after they sleep.

At Emory University in Atlanta, Georgia, a researcher wants to help babies communicate with their parents. Babies have no ability, however, to say what is on their minds. So they communicate through behavior that often leaves parents clueless.

"I think it is extremely important to help parents better understand the apparent erratic behavior of their children," said Dr. Michelle Lample, who headed a study on sleep and growth at Emory University.

It is this erratic behavior, she said, that leaves parents frustrated. "They say, 'The most challenging part of being a parent of an infant is wanting to do what is best for them. And wanting to respond to them. And when they [the babies] cry, and when their behavior patterns are so erratic, it makes me feel, as a parent, very insecure.'"

So Lample asked parents to write down everything their babies did, including when they slept and when they ate. Researchers also visited the homes and recorded their own data on 23 babies for 17 months.

"This particular study was designed to ask the specific question: Is there an association between sleep behavior and growth spurts? And this study documents that yes, indeed, the common perception that increased sleep precedes growth is in fact the case," said Lample.

The researchers also found that longer periods of sleep in both girls and boys also predicted increased weight. What's more, the study showed differences between the sleep patterns of boys and girls. Boys would sleep for longer periods of time, while girls would sleep for a long stretch, and then add a nap. Dr. Lample said the research shows that seemingly erratic sleep behavior is a normal part of development.

What's next? Dr. Lample wants to review the data to see if babies tend to eat more before a growth spurt.