Contributions of specific sleep stages to cognitive processes are increasingly understood. Non-REM sleep is particularly implicated in episodic memory consolidation, whilst REM sleep preferentially consolidates and regulates emotional information, and gives rise to creativity and insight. Dream content reflects these processes: non-REM dreams are more likely to picture episodic memories, whereas REM dreams are more emotional and bizarre. However, across-the-night differences in the memory sources of dream content, as opposed to sleep stage differences, are less well understood. In the present study, 68 participants were awoken from sleep in the early and late night and recorded their dreams and waking-life activities. Early-night dreams were more clearly relatable to (or continuous with) waking life than late-night dreams. Late-night dreams were more emotional-important, more time orientation varied, and more hyperassociative, than early-night dreams. These dream content differences may underlie the mental content that accompanies sleep processes like memory consolidation, emotion-processing, and creativity.

人们越来越了解特定睡眠阶段对认知过程的贡献。非快速眼动睡眠尤其与情节记忆巩固有关，而快速眼动睡眠优先巩固和调节情绪信息，并产生创造力和洞察力。梦的内容反映了这些过程：非快速眼动梦更可能描绘情节记忆，而快速眼动梦更情绪化和离奇。然而，与睡眠阶段差异相反，梦内容的记忆源的跨夜差异还不太清楚。在本研究中，68 名参与者在清晨和深夜从睡眠中醒来，并记录了他们的梦境和清醒时的活动。与深夜梦相比，早梦更明显地与清醒的生活相关（或持续）。与早梦相比，深夜梦在情感上更重要，时间取向更多样化，也更具有高度联想性。这些梦境内容差异可能是伴随睡眠过程（如记忆巩固、情绪处理和创造力）产生的心理内容的基础。