Although some support exists that sleep is more beneficial for certain kinds of memories, the majority of studies does not support such an effect

Davidson, Per, Peter Jönsson, Ingegerd Carlsson, and Edward Pace-Schott. 2020. “Does Sleep Selectively Strengthen Certain Memories over Others? A Critical Review of the Literature.” PsyArXiv. August 21. doi:10.31234/osf.io/umn9r

Abstract: Sleep has been found to have a beneficial effect on memory consolidation. It has furthermore frequently been suggested that sleep does not strengthen all memories equally. The aim of this literature review was to examine the studies that have measured whether sleep selectively strengthens certain kinds of declarative memories more than others, depending on such factors as emotion, reward, test-expectancy or different instructions during encoding. The review of this literature revealed that although some support exists that sleep is more beneficial for certain kinds of memories, the majority of studies does not support such an effect. A second aim of this review was to examine which factors during sleep that have been found to selectively benefit certain memories over others, with a special focus on the often-suggested claim that rapid eye movement sleep primarily consolidates emotional memories. The review of this literature revealed that no sleep variable has been reliably found to be specifically associated with the consolidation of certain kinds of memories over others.