SSS 2011-05-04（在线收听）

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

Parents wring their hands over infant sleep patterns. And so when those patterns change, parents tend to panic. But if your baby is sleeping more or napping at weird times, maybe he or she is just growing. So says a study in the journal Sleep.

It's known that levels of growth hormone rise during certain stages of sleep. So researchers wanted to know more about the link between sleep and growth. They recruited the parents of 23 infants. The parents took careful real-time notes on infant sleep patterns for between four and 17 months. They also noted whether the babies were breast- or bottle-fed, and whether they had signs of illness such as rashes or diarrhea. And the babies' body length and weight were measured regularly.

The researchers found that periods where infants slept more overall corresponded with growth spurts and also a gain in weight and body fat. Both genders experienced that correlation, though boys had more and shorter sleep episodes than girls. The scientists note that increases in sleep may lead to increases in waking, as growing bones produce growing pains. So if your baby's sleeping a little funny, maybe she's just growing up.

"Rock a bye baby, on the tree top."

Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.

"When the wind blows, the cradle will rock.Rock,rock,rock a bye baby."