Has your baby started to nap more often? This may be a sign that a growth spurt is on its way. A new study has confirmed a longstanding theory – infant sleeping patterns are related to growth spurts in babies. This theory has never been proven until now.
According to a new research study in the recent issue of Sleep, babies who start to take more naps, or sleep for longer periods of time, are more likely to undergo a growth spurt within the next two days. So, if you think your baby has suddenly gotten bigger overnight, you might be right!
The Science Behind Baby Growth Spurts and Sleep Patterns
Researchers at Emory University asked 23 parents to keep daily sleep records for their babies (9 boys, 14 girls), starting at 12 days old. The parents detailed when their children fell asleep and woke up, in addition to whether the babies were breastfed or formula-fed, and whether the children developed any signs of illness (such as diarrhea, rash, fever, or vomiting).
The study’s authors measured the infant’s length on a regular basis (some were measured every day; others were measured twice a week), and they cross-referenced this information with the babies’ sleep records.
When the infant’s sleep patterns started changing – when the babies started taking more naps, or sleeping more – this was usually followed by a growth spurt. With each additional nap the baby took, they were 43 percent more likely to have a growth spurt. And for each additional hour of sleep the babies got during these sleep peaks, they were 20 percent more likely to grow. Growth spurts in these babies typically occurred within 48 hours of these bursts of extra sleep.
On average, growth spurts in babies caused them to sleep about 4.5 extra hours each day over two days. This roughly equates to three extra naps.
Baby Growth Spurts: Boys vs. Girls, Breastfed vs. Bottle-fed
When the babies started to sleep more and longer, they grew in length, and they also got heavier, especially around their bellies. There was also a difference among the boy and girl babies. The baby boys slept for shorter periods of time, but they napped more often than the little girls.
Breastfed babies typically took shorter, more frequent naps, compared to the bottle-fed babies.
This study didn’t explain how sleep affects babies growth, but the researchers theorize that it may be due to hormonal signals during sleep that boost the secretion of growth hormones in these babies.