During wakefulness the brain accumulates waste such as lactic acid and damaged proteins. While we sleep, cerebrospinal fluid (CSF) waves wash these metabolites away, keeping the brain healthy. MIT researchers have shown that brief bursts of pink noise delivered during sleep can amplify CSF wave amplitude, potentially making sleep more restorative.\ \ Pink noise contains all audible frequencies, with lower pitches louder and higher pitches softer, sounding like steady rain or a distant waterfall. The experiment used 50‑millisecond bursts timed to the peak of slow‑wave activity. To achieve this timing, participants’ EEG and fMRI were recorded simultaneously; the magnetic field of fMRI normally contaminates EEG, so the team devised a processing pipeline that removes the interference in under 100 ms. An additional predictive algorithm estimated when the slow‑wave peaks would occur, allowing the pink‑noise pulse to be delivered at the optimal moment.\ \ In a cohort of 14 healthy volunteers, the auditory stimulus—quiet enough not to awaken the sleeper—significantly increased the amplitude of both slow electrical waves and CSF waves. fMRI revealed that slow waves cause blood vessels to constrict and dilate, acting like a pump that drives CSF out of the brain.\ \ The researchers now aim to test whether boosting CSF flow can improve restorative sleep in people with insomnia and whether it can mitigate neurodegenerative diseases such as Alzheimer’s that are driven by protein aggregates. Levitt has founded a company to develop a head‑band device that can be used at home to deliver precisely timed auditory cues.\ \ The work was funded by a McKnight Scholar Award, a Sloan Fellowship, NIH, and several other foundations.\ \ Review