In case you need to be convinced of the value of a good night’s sleep, a new study published in the Oct. 18 issue of Science found that sleep can literally clear your mind. Led by Maiken Nedergaard, M.D., D.M.Sc., co-director of the Center for Translational Neuromedicine at the University of Rochester Medical Center in New York, the investigators discovered that, in mice, sleep may induce "enhanced removal of potentially neurotoxic waste products that accumulate" in the central nervous system during waking hours.
In this National Institute of Neurological Disorders and Stroke-funded research, scientists injected dye into the cerebrospinal fluid of mice, and watched it flow through their brains while also monitoring electrical brain activity. When the mice were either asleep or under anesthesia, the dye flowed rapidly. When these same mice were awake, on the other hand, the dye hardly moved.
“We were surprised by how little flow there was into the brain when the mice were awake,” said Dr. Nedergaard in a press release. “It suggested that the space between brain cells changed greatly between conscious and unconscious states.”
Dr. Nedergaard and colleagues then used electrodes to measure the space between brain cells, and found a 60-percent increase when the mice were unconscious (asleep or under anesthesia). They also found that injected amyloid-beta (which plays a role in Alzheimer's disease) disappeared faster in mice when they were asleep.
These findings suggest a new role for sleep in health and disease, according to Dr. Nedergaard and colleagues.
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