Contributor: Dave Rosenberg, MD Educational Pearls: White noise is all the surrounding sound frequencies mixed together that your brain tunes down so you don’t get distracted while you're sleeping Pink noise, or deep soothing noises, is the accentuated bass sounds like falling rain or waves crashing your brain keys into while sleeping. Brain electrical waves during stage 4 sleep (the deepest of sleeps), cause sudden increases and decreases in cerebral blood flow allowing for CSF washing of the brain, which helps eliminate beta amyloid - the misfolded protein linked to Alzheimers Pink noise during sleep has been shown to increase stage 4, creating more CSF washout of beta amyloid. References 1. Spinedi, E. Cardinali, DP. Neuroendocrine Metabolic Dysfunction and Sleep Disturbances in Neurodegenerative Disorders: Focus on Alzhimer's Disease and Melatonin. Neuroendocrinology. 2019;108(4):354-364. doi: 10.1159/000494889. Epub 2018 Oct 28. 2. Zee, P. Papalambros NA. et al. Acoustic Enhancement of Sleep Slow Oscillations and Concomitant Memory Improvement in Older Adults. Front Hum Neurosci. 2017 Mar 8;11:109. doi: 10.3389/fnhum.2017.00109. eCollection 2017.   Summarized by Jackson Roos, MS3 | Edited by Erik Verzemnieks, MD