from another website.. "tACS: Transcranial Alternating Current Stimulation (tACS) is a noninvasive, low-level alternating current applied to the cranium. New research out today suggests it expedites memory consolidation while you sleep. As with the above noninvasive transcranial stimulation techniques, it is not fully understood how it works and the long-term effects are unknown." - https://www.forbes.com/sites/andreamorris/2018/07/23/can-we-...