Multiple memories can be simultaneously reactivated during sleep as effectively as a single memory

This study investigated whether reactivating multiple memories during sleep interferes with memory consolidation. Participants learned the location of objects grouped into sets of one, two, or six items. Sounds were presented during sleep to reactivate memories for half the groups. Memory benefits for cued items were independent of group size, suggesting simultaneous reactivation. Sleep spindles and delta-theta power modulations were sensitive to group size, reflecting learning extent. The findings demonstrate that multiple memories can be consolidated in parallel without compromising individual memory benefits.

Eitan Schechtman, James W Antony, Anna Lampe, Brianna J Wilson, Kenneth A Norman, Ken A Paller