Sleep boosts production of brain cells


2013-09-11 10:59

While we all know that a good night’s sleep helps us feel refreshed and re-energized, researchers from the University of Wisconsin in Madison recently discovered that sleep also increases the reproduction of cells involved in brain repair.

The researchers found that sleep boosts the reproduction of cells that go on to form myelin, which is the insulating material on nerve cell projections in the brain and spinal cord, according to a new study published September 4 in The Journal of Neuroscience. The findings could lead scientists to new insights about the role sleep plays in brain repair and growth.

Previous studies have revealed that multiple genes are switched on when we’re sleeping and switched off when we’re awake. However, it was unclear how sleep affects certain cell types, such as oligodendrocytes, which make myelin in the healthy brain and in response to injury. Similar to the insulation around an electrical wire, myelin allows electrical impulses to move rapidly from one cell to the next.

The researchers used mice for the current study, analyzing gene activity of oligodendrocytes in the cerebral cortex of mice that slept, and then comparing these with gene activity of mice that stayed awake.

As a result, the research team found that in the mice that slept, the genes promoting myelin formation were turned on. In the mice that stayed awake, however, the genes implicated in cell death and the cellular stress response were turned on.

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Further analysis revealed that the reproduction of oligodendrocyte precursor cells (cells that become oligodendrocytes), doubles during sleep, particularly during rapid eye movement (REM), which is associated with dreaming.

"These findings hint at how sleep or lack of sleep might repair or damage the brain," said Mehdi Tafti, PhD, who studies sleep at the University of Lausanne in Switzerland, but was not involved with this study.

"For a long time, sleep researchers focused on how the activity of nerve cells differs when animals are awake versus when they are asleep," said Chiara Cirelli, MD, PhD, from the Center for Sleep and Consciousness at the University of Wisconsin, who was involved with this study.

"Now it is clear that the way other supporting cells in the nervous system operate also changes significantly depending on whether the animal is asleep or awake," Dr. Cirelli said.

She also pointed out that these findings may suggest that extreme or chronic lack of sleep could trigger some symptoms associated with multiple sclerosis (MS), which is a progressive brain disease associated with myelin damage, although she added that further studies are needed to determine whether such association exists.

SOURCE: The Journal of Neuroscience, Effects of Sleep and Wake on Oligodendrocytes and Their Precursors (September 4, 2013), 33(36): 14288-14300; doi: 10.1523/ JNEUROSCI.5102-12.2013

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