Babies wake up taller after a sleep

London: It seems grandma was right –babies do wake up taller after a sleep, says a new study which has found a link between daily growth and shut-eye.

An international team has carried out the study and found that the babies bed down for 4.5 hours extra every day for two days just before a growth spurt, taking an average of three extra naps a day.

The growth spurt will occur within 48 hours of these increased bursts of sleep. And the more sleep a baby starts to need, the more likely they are to experience a growth spurt, say the researchers.

Figures show the probability a baby will experience a growth spurt increases by an average of 43 per cent for each additional sleep episode. And it shoots up by 20 per cent for each extra hour of sleep a baby takes, `Daily Mail` reported.

The research paves the way to a better understanding of newborns and allows parents to predict when their baby is going to grow, says the team.

According to lead researcher Michelle Lampl of Emory University in Atlanta, "The results demonstrate empirically that growth spurts not only occur during sleep but are significantly influenced by sleep.

"Longer sleep corresponds with greater growth in body length. On a practical, everyday level, it helps parents understand their infant`s behaviour and patterns."

During the study, 23 parents recorded daily sleep records for their infants, starting on average when the babies were 12 days old. For between four and 17 months, the babies growth was assessed.

The researchers noticed the secretion of the growth hormone increased after babies went to sleep and during the stage of slow wave sleep. They claim this change in hormonal signals during sleep could stimulate bone growth, which would support anecdotal reports of "growing pains", the aching limbs that can wake children at night.

However, some sleep alterations occurred without a growth spurt, and not every growth spurt was preceded by a burst of sleep.

But Dr Lampl said that in, some cases, growth may have occurred in other parts of the body. "It opens another door to understanding why we sleep. We now know sleep is a contributing factor to growth spurts at the biological level."

The study has been published in the `Sleep` journal.