Can sleep clean out the junk from your brain?
The exact reason why we sleep has long been one of the greatest mysteries of modern science, but a recent study offers a theory corroborated earlier research that sleep may act as a way for your brain to flush out all the waste that your neurons produce throughout the day.
The researchers focused on the movement of fluids between neurons in mice during the awake and sleep states. They found that there was very little movement of fluids during awake states, and that movement rapidly increased during sleep. These fluids act as drainage for toxic waste that the brain is likely too busy to purge during the day.
A 2019 study built on this research, showing for the first time that this mechanism is present in humans and that the fluid present in our brains and spinal cords, called cerebrospinal fluid, appears to synchronize with brainwaves to help remove metabolic trash.
Maiken Nedergaard, one of the authors of the 2013 study, commented on the implications that these studies may have on shift workers, as the sleep loss that they experience is likely causing long term damage.
In the short term, the build-up of proteins and junk can make you feel foggy after one night of sleep loss as the neurons struggle a bit more to connect with each other.
But in the long term, this research can shed light on diseases like Alzheimers, as it is toxic protein plaques that play a key role in memory loss and other cognitive impairments experienced by individuals suffering from many neurodegenerative diseases. Researchers don’t yet know if these plaques are a cause or a result of neurodegenerative disease.
You can read the 2019 study ‘coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep’ in Science here: https://science.sciencemag.org/content/366/6465/628
You can read the 2013 study ‘Sleep drives metabolite clearance from the adult brain, in Science here: https://www.ncbi.nlm.nih.gov/pubmed/24136970