RIKEN Center study links cerebrospinal fluid flow to deep sleep

A new study published in the Proceedings of the National Academy of Sciences (PNAS) by the RIKEN Center for Brain Science in Japan has revealed how cerebrospinal fluid (CSF) flows during deep sleep. Researchers discovered that CSF circulation is not random but synchronizes with the electrical waves produced by the brain during its deepest sleep phases.

By combining functional magnetic resonance imaging (fMRI) with polysomnography, scientists were able to record brain activity and CSF changes simultaneously. The findings show that during slow-wave sleep, rhythmic fluctuations in brain waves are directly linked to repetitive, mild variations in the CSF signal. This connection suggests a mechanism for the brain's cleaning process, a phenomenon previously observed only in animals, now confirmed in humans.