Need Brains?- Sleep!

Space between brain cells increases by 60% in sleep to replace buildup and prevent dementias



Researchers have discovered that well rested brains are less poisoned. Writing in the most recent issue of Science, researchers from the Center for Translational Neuromedicine at the University of Rochester Medical Center in New York studied mice and discovered that the space between brain cells increases during sleep.

“Sleep changes the cellular structure of the brain. It appears to be a completely different state,” said Maiken Nedergaard, MD, DMSc, co-director of the Center and a leader of the study.

The brain has plumbing called the glymphatic system that apparently opens during sleep and allows fluid to interchange and flow rapidly in and out as if it is draining buildup and replacing with cleaner.

The researchers used dye to observe the flow during sleep and wakeful hours. “We were surprised by how little flow there was into the brain when the mice were awake,” said Dr Nedergaard. “It suggested that the space between brain cells changed greatly between conscious and unconscious states.”

The cavernous space inside the brain increased by 60 percent when the mice were asleep or anesthetized, according to the study.

Brain cells known as glia control flow through the glymphatic system by shrinking or swelling. Previous studies suggest that toxic molecules involved in neurodegenerative disorders accumulate in the space between brain cells.

“We need sleep. It cleans up the brain,” said Dr Nedergaard.

L. Xie, H. Kang, Q. Xu, M. J. Chen, Y. Liao, M. Thiyagarajan, J. O'Donnell, D. J. Christensen, C. Nicholson, J. J. Iliff, T. Takano, R. Deane, M. Nedergaard. Sleep Drives Metabolite Clearance from the Adult Brain. Science, 2013; 342 (6156): 373 DOI: 10.1126/science.1241224
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