Blood flows out and cerebrospinal fluid flows into the sleeping brain | Science News
During non-REM sleep, oxygen-rich blood (colored red) flows out of the brain just before a wave of cerebrospinal fluid (blue) rolls in, entering from a lower part called the fourth ventricle. That cerebrospinal fluid may help clean harmful proteins out of the brain.
Read more: https://www.sciencenews.org/article/sleep-may-trigger-rhythmic-power-washing-brain
Video: Laura Lewis, N. Fultz et al/Science 2019