Dreams reflect nocturnal cognitive processes: Early-night dreams are more continuous with waking life, and late-night dreams are more emotional and hyperassociative

Dreams reflect nocturnal cognitive processes: Early-night dreams are more continuous with waking life, and late-night dreams are more emotional and hyperassociative. J. E. Malinowski, C. L. Horton. Consciousness and Cognition, Volume 88, February 2021, 103071. https://doi.org/10.1016/j.concog.2020.103071

Rolf Degen's take: https://twitter.com/DegenRolf/status/1342363251238195201

Highlights

• Across-the-night dream content differences were investigated.

• Overt continuity with waking life was greater in the early night.

• Hyperassociativity, metaphoricity, and emotionality were greater in the late night.

• Dream content differences map onto alternating across-the-night cognitive functions of sleep.

Abstract: 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.

Keywords: DreamingREM and non-REM sleepThe Continuity HypothesisMetaphorHyperassociativity