Wunderlin et al. recently published a systematic review and meta analysis article in the Journal of Sleep looking at acoustic stimulation during slow-wave sleep. There are a range of devices developed that deliver an acoustic sound designed to enhance the low-frequency, high amplitude EEG oscillations during slow wave sleep (deep sleep). In doing so, it is thought that the positive effects (episodic memory consolidation) of this EEG activity would also be enhanced. These devices usually consist of some form of EEG measurement (to identify the slow wave sleep activity), and a sound delivering device (eg headphones) to deliver the acoustic stimulation.
The literature suggests the effects of these increases in slow wave activity vary quite a lot. This study looked to assess the benefit, if any that this enhanced EEG activity provides.
Acoustic enhancement of slow wave sleep tends to increase the overnight consolidation of episodic memory but the effects remain small. Currently, they concluded that the evidence is not sufficient to recommend the use of commercially available devices.
Marina Wunderlin, Marc A Züst, Elisabeth Hertenstein, Kristoffer D Fehér, Carlotta L Schneider, Stefan Klöppel, Christoph Nissen, Modulating overnight memory consolidation by acoustic stimulation during slow wave sleep – a systematic review and meta-analysis, Sleep, 2021;, zsaa296, https://doi.org/10.1093/sleep/zsaa296
