03/21/2013 07:57 am ET

Changes In Adolescents' Brains During Sleep Revealed In New Study

A new sleep study reveals the multitude of changes the brain undergoes during adolescence.

The study, published in the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, included 28 kids ages 6 to 10. The kids' brains were examined with an electroencephalogram (EEG), which tracks brain changes, as they slept for two nights every six months.

Researchers were able to see changes in the brain's neuronal connections throughout time, finding that the density of the synapses in the brain are the densest when the children are at age 8. From then on, density decreases, with it decreasing the fastest between ages 12 and 16-1/2.

This decrease in brain density is a natural thing with growing up, researchers noted -- having a huge number of synapses in the brain is good when you are young because it believed to help with injury recovery and adaptation, but when you get older, they begin to get in the way with thinking skills.

"Discovering that such extensive neuronal remodeling occurs within this 4-1/2 year timeframe during late adolescence and the early teen years confirms our view that the sleep EEG indexes a crucial aspect of the timing of brain development," study researcher Irwin Feinberg, director of the University of California-Davis Sleep Laboratory and professor emeritus of psychiatry and behavioral sciences, said in a statement.

The study confirms that not only does the body go through a multitude of changes during puberty, but the brain does, too, the researchers said.

"These data further document the powerful and complex link between sleep and brain maturation. Understanding this relationship would shed light on both brain development and the function of sleep," they wrote in the study.

A 2011 piece in National Geographic well explains the "remodeling" process that takes place in brains during adolescence:

For starters, the brain's axons -- the long nerve fibers that neurons use to send signals to other neurons -- become gradually more insulated with a fatty substance called myelin (the brain's white matter), eventually boosting the axons' transmission speed up to a hundred times. Meanwhile, dendrites, the branchlike extensions that neurons use to receive signals from nearby axons, grow twiggier, and the most heavily used synapses -- the little chemical junctures across which axons and dendrites pass notes -- grow richer and stronger. At the same time, synapses that see little use begin to wither. This synaptic pruning, as it is called, causes the brain's cortex -- the outer layer of gray matter where we do much of our conscious and complicated thinking -- to become thinner but more efficient.



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