While young children sleep, connections between the left and the right hemispheres of their brain strengthen by as much as 20 per cent, which may help brain functions mature, according to a new study.
Researchers at the University of Colorado Boulder used electroencephalograms, or EEGs, to measure the brain activity of eight sleeping children multiple times at the ages of 2, 3 and 5 years.
"Interestingly, during a night of sleep, connections weakened within hemispheres but strengthened between hemispheres," said postdoctoral researcher Salome Kurth.
Scientists have known that the brain changes drastically during early childhood: New connections are formed, others are removed and a fatty layer called "myelin" forms around nerve fibres in the brain.
The growth of myelin strengthens the connections by speeding up the transfer of information.
Maturation of nerve fibres leads to improvement in skills such as language, attention and impulse control. But it is still not clear what role sleep plays in the development of such brain connections.
In the new study, the researchers looked at differences in brain activity during sleep as the children got older and differences in brain activity of each child over a night's sleep.
They found that connections in the brain generally became stronger during sleep as the children aged. They also found that the strength of the connections between the left and right hemispheres increased by as much as 20 per cent over a night's sleep.
"There are strong indications that sleep and brain maturation are closely related, but at this time, it is not known how sleep leads to changes in brain structure," Kurth said.
"I believe inadequate sleep in childhood may affect the maturation of the brain related to the emergence of developmental or mood disorders," Kurth said.
The study was published in the journal Brain Sciences.
