Spindle-dependent memory consolidation in healthy adults: A meta-analysis
Accumulating evidence suggests a central role for sleep spindles in the consolidation of new memories. However, no metaanalysis of the association between sleep spindles and memory performance has been conducted so far. Here, we report meta-analytical evidence for spindle-memory associations and investigate how multiple factors, including memory type, spindle type, spindle characteristics, and EEG topography affect this relationship. The literature search yielded 53 studies reporting 1427 effect sizes, resulting in a small to moderate effect for the average association. We further found that spindle-memory associations were significantly stronger for procedural memory than for declarative memory. Neither spindle types nor EEG scalp topography had an impact on the strength of the spindle-memory relation, but we observed a distinct functional role of global and fast sleep spindles, especially for procedural memory. We also found a moderation effect of spindle characteristics, with power showing the largest effect sizes. Collectively, our findings suggest that sleep spindles are involved in learning, thereby representing a general physiological mechanism for memory consolidation. HighlightsO_LISpindle measures showed a small to medium-sized association with memory performance. C_LIO_LIThis relationship was stronger for procedural memory than declarative memory. C_LIO_LINo moderation effects of spindle type and EEG scalp topography have been observed. C_LIO_LISpindle power emerged as the strongest predictors. C_LIO_LINaps showed similar spindle-related consolidation mechanisms to whole-night sleep. C_LI