LMS Issue 6; 2013 | Page 10

10? LMS? Issue 6 | 2013 News | International & Local Good Sleep, Sweeps Clean F or centuries, the purpose of sleep has vexed scientists. However, researchers at the University of Rochester Medical Centre (URMC) in New York believe that they may have discovered a plausible explanation for why humans need sleep. In their research paper, which was published in the October edition of the journal Science, this group of scientists described how cerebrospinal fluid (CSF) is pumped throughout the brain during sleep to remove all the toxins that build up in there during the waking hours. Thus, sleeping is necessary to literally clear the mind. Maiken Nedergaard, Co-director of the Centre for Translational Neuromedicine and his cohort of researchers performed a series of experiments on sleeping mice. These experiments included injecting a dye into the CSF of the mice and monitoring its flow throughout the brain. They discovered that in the sleeping rodents, the CSF appeared to flow rapidly through the brain tissue. However, when these same rodents were awake, the dyed CSF flow rate was greatly reduced. Nedergaard and his team also found that the cells in the brains of the mice ap­ eared to shrink during sleep. After p measuring the shrinkage of these cells, they found that the reduction in the size of the cells allowed for the channels between them to become almost 60% larger, which allowed the CSF to flow almost 10 times faster than in a mouse that was awake. 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