Each night, the sleeping brain performs a quiet act of renewal — cerebrospinal fluid moves through neural tissue like a slow tide, carrying away the metabolic residue of waking life. MIT researchers have now learned to deepen this ancient rhythm, using precisely timed bursts of pink noise to amplify the brain's own slow electrical waves and, with them, the fluid currents that cleanse it. The discovery, published in Science Translational Medicine, suggests that the border between sleep science and neurodegenerative medicine may be narrower than we once believed.