Beauty Sleep isn’t just for Princesses

Picture provided by Science News. Depicts colored tracers penetrate more deeply into a mouse’s brain when it’s asleep (left, red tracer) than awake (right, green tracer).

Sleep has always been a significant biological process that has intrigued people from ancient to modern times. Ancient cultures held different views on sleep depending on their nomadic or sedentary lifestyle and survival needs. Sleep is an important part of our circadian rhythm and holds natural rejuvenating qualities. Many of the benefits of sleep are being revealed with the aid of new technologies. Dr. Maiken Nedergaard, from the University of Rochester Medical Center, is a pioneer in the scientific community. Her research team recently conducted a study to determine if during sleep the brain cleanses itself by flushing out unwanted toxins that accumulate during active hours. In order to study this, the research team injected dye into mice’s cerebrospinal fluid, which is the clear liquid that surrounds the brain and spinal cord, to observe the travel route of the dye through the brain. The data showed that the dye flowed when the mice were asleep or unconscious and remained stagnant when the mice were awake. This helped support their hypothesis because the cell structure must have shifted during sleep creating space between the brain cells, which allowed the dye to be flushed out. The increase in space between the brain cells is most likely controlled by the glymphatic system, which regulates the flow of cerebrospinal fluid in the brain. To further investigate the increased space between the brain cells, the researchers tested it with electrodes. They inserted the electrodes into both alert and unconscious mice’s brain and measured the distance.  The scientists compared the results and the space increased by 60% in sleeping mice. Additional support of this is that the glia cells control the shrinking and swelling of the glymphatic system. When noradrenaline, an arousal hormone responsible for increasing the control cell volume, is blocked it induces asleep or unconsciousness and increases fluid flow and brain cell spacing. Lastly, researchers conducted a test to see if there is a connection between the glymphatic system and neurodegenerative disorders. They injected beta-amyloid, which is a protein associated with Alzheimer’s disease, into the brain to measure how long it remained in the brain when asleep or awake. Scientists observed that the beta-amyloid was flushed out quicker when the mice were asleep. This outcome supports that the brain normally clears out toxic molecules from the brain. The glymphatic system could be the new target for treating disorders and be a major breakthrough in the medical field. There are many aspects and complex workings of the brain we have not discovered yet but we are slowly gaining more understanding of the biological processes.

Saey, Tina Hesman. Sleep allows brain to wash out junk. Science News. Science News Magazine of the Society for Science and the Public, 17 Oct. 2013. Web. 23 Oct. 2013.