Memory retention following acoustic stimulation in slow-wave sleep: a meta-analytic review of replicability and measurement quality

Abstract

The role of slow oscillations and spindles during sleep on memory retention has become an area of great interest in the recent decade. Accordingly, there are multiple studies that examine the efficacy of acoustic stimulation during sleep to facilitate slow oscillations and associated memory retention. Here, we run meta-analyses on a current set of 14 studies that use audible noise-burst sound stimulation to modulate overnight retention of word pairs (kS = 12 studies, kES = 14 effect sizes, n = 206 subjects). Our meta-analyses demonstrate a steady, yearly decline in effect size that accounts for 91.8% of the heterogeneity between studies. We find that the predicted effect on memory retention in 2013 favored the acoustic stimulation condition at dδ = 0.99 (95% CI [0.49, 1.49]), while the predicted effect in 2021 declined to a moderate and significant effect favoring no acoustic stimulation at dδ = −0.39 (95% CI [−0.73, −0.05]). Our meta-regression model finds no coded study-level characteristics could account for the decline in effect sizes over time other than the publication date alone. Using available data, we estimate that 34% of subjects are not actually blind to the acoustic stimulation condition due to hearing acoustic stimulation during sleep. In addition, we find that the test-retest reliability of memory retention scores is nearly zero (ρd = 0.01, 95% CI [−0.18, 0.21]), and through simulation demonstrate the impact this has on statistical power and observed effect sizes. Based on our analyses, we discuss the need for larger sample sizes, true placebo controls, age range restrictions, open-data sharing, and improvements in the reliability of memory retention tasks.

Closed-loop auditory stimulation of sleep slow oscillations: Basic principles and best practices

“…In summary, CLAS has been used to probe the role of slow oscillations and their relationship with sleep spindles in memory consolidation with a broad range of memory tasks, however a recent metaanalysis reported a steady decline in effect size of memory studies using CLAS over the last decade (Harlow et al, 2023). The inconsistent results of CLAS in enhancing memory consolidation raise questions about the role of the type of memory task and the subtleties of stimulation protocols interacting with different types of oscillations in the effectiveness of CLAS.…”

Electrophysiological mechanisms of memory consolidation in human non-rapid eye movement sleep

“…Current work assessing the boundary conditions of auditory stimulation (e.g. the types of memory that receive a stimulation benefit) [74,79,80] and optimal stimulation parameters (e.g. duration of stimulation) [81,82] will serve to improve this method further.…”

Treatments and regulatory mechanisms of acoustic stimuli on mood disorders and neurological diseases

“…For centuries, music or beneficial noise have been applied as a non-pharmaceutical therapeutic intervention to enhance physiological and psychological strength in humans (Chen et al, 2022;Lorek et al, 2023). Acoustic stimulus has been shown to improve one's attention, memory and cognitive flexibility, to influence psychomotor functioning, and to synchronize motor behaviors through rhythm and beat (Braem and Egner, 2018;Terry et al, 2020;Uddin, 2021;Harlow et al, 2023). Music therapies also can reduce arousal levels, and help people gain benefit in managing sleep disorders (Loewy, 2020;Petrovsky et al, 2020).…”