A new study shows that daily growth and sleep are inextricably linked in babies — in fact, infants wake up taller right after sleeping.
The Emory University study helps parents understand that irregular sleep behavior is a normal part of growth and development.
“Sleep irregularities can be distressing to parents,” said lead author Michelle Lampl, M.D., Ph.D. “However, these findings give babies a voice that helps parents understand them and show that seemingly erratic sleep behavior is a normal part of development. Babies really aren’t trying to be difficult.”
A baby’s growth spurts are linked to an increase in total daily hours of sleep as well as an increase in the number of daily sleep bouts — the time between falling asleep and waking up.
“Little is known about the biology of growth spurts,” said Lampl. “Our data open the window to further scientific study of the mechanisms and pathways that underlie saltatory (sudden) growth.”
The study shows that longer sleep bouts end with an increase in weight and body-fat composition tied to an increase in length. Therefore, not only is sleep tied to getting taller, but it also increases the baby’s weight and abdominal fat.
Furthermore, the research was able to differentiate between sleep patterns related to growth in boys and girls. “Growth spurts were associated with increased sleep bout duration in boys compared with girls and increased number of sleep bouts in girls compared with boys,” said Lampl.
Overall, boys displayed more frequent, but shorter, sleep bouts than girls. Also, breastfeeding — as opposed to formula feeding — was linked to more and shorter sleep bouts. However, neither the baby’s gender nor breastfeeding had significant effects on total daily sleep time.
Unlike past research, this study did not rely on parents having to remember their infant’s sleep patterns and growth. Instead, data on 23 infants were recorded throughout the day over a four- to 17-month span. Mothers recorded daily their baby’s sleep patterns in diaries and also noted whether babies were breastfeeding, formula feeding, or both and whether their infant showed signs of illness, such as vomiting, diarrhea, fever or rash.
Lampl’s study is published in the May 1 issue of SLEEP.
Source: Emory University