Aversive memories can be weakened during human sleep via the reactivation of positive interfering memories

Abstract

Recollecting painful or traumatic experiences can be deeply troubling. Sleep may offer an opportunity to reduce such suffering. Accordingly, we developed a procedure to weaken older aversive memories by reactivating newer positive memories during sleep, thereby producing interference. Participants viewed 48 nonsense words each paired a unique aversive image, followed by overnight sleep. The next day, participants learned additional associations between half of the words and positive images, creating interference. During non-rapid-eye-movement sleep that night, memory cues were unobstruisvely delivered. Upon waking, presenting cues associated with both aversive and positive images during sleep, as opposed to not presenting cues, weakened aversive memory recall while increasing positive memory intrusions. Substantiating these memory benefits, computational modeling revealed that cueing facilitated evidence accumulation toward positive affect judgments. Moreover, cue-elicited theta brain rhythms during sleep predominantly predicted recall of positive memories. A noninvasive sleep intervention can thus modify aversive recollection and affective responses.