Increased bursts of sleep in infants are linked with growth spurts, new research indicates.
The new study included 23 parents who kept daily sleep records for their infants (14 girls, nine boys), who were 12 days old at the start of the study. The researchers analysed the total of 5,798 daily sleep records and also tracked the infants' growth.
The infants had uneven bursts of sleep, with the amount of sleep over a 24-hour period increasing at irregular intervals by an average of 4.5 hours per day for two days, the study found. In addition, the infants' number of sleep episodes per day also increased in intermittent surges of an average of three extra naps per day for two days.
There was a significant association between these increases in sleep and growth spurts in body length, which tended to occur within 48 hours of the sleep bursts. The researchers determined that the likelihood of a growth spurt increased by about 43% for each additional sleep episode and by 20% for each extra hour of sleep.
The study is published in the journal Sleep.
Baby growth influenced by sleep
"The results demonstrate empirically that growth spurts not only occur during sleep but are significantly influenced by sleep," lead investigator Dr Michelle Lampl, a professor in the department of anthropology at Emory University in Atlanta, said in a news release from the American Academy of Sleep Medicine. "Longer sleep corresponds with greater growth in body length."
The nature of the link between increased sleep and growth in infants isn't clear, but it is known that the secretion of growth hormone increases during sleep, Lampl said.
The findings may be helpful for parents, who can become frustrated by the variability and unpredictability of an infant's sleep patterns, she added.
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