Activating a remote emotional memory just before sleep can induce dreams about that memory. In a study with 34 participants, those who recalled and wrote about an emotionally negative remote memory before a daytime nap later had dreams judged to contain content from that memory more than from a control task. Participants also rated their dreams as more emotionally negative after the memory task. The findings suggest that dream content can be experimentally influenced by reactivating older memories, possibly reflecting memory reconsolidation during sleep.
Recalling a personal emotional memory before sleep did not make people dream about that memory more than writing about a neutral topic. However, dreams after recalling an angry memory were rated as more negative in emotion, especially the first dream reported. This suggests that while pre-sleep experiences rarely appear directly in dream content, emotional stimuli can influence the emotional tone of dreams, possibly reflecting emotional memory consolidation or a general effect of pre-sleep mood on dream emotion.