Dreams reflect nocturnal cognitive processes: Early-night dreams are more continuous with waking life, and late-night dreams are more emotional and hyperassociative.
Consciousness and Cognition February 1, 2021 J E Malinowski, C L Horton
Dreams from the early night are more clearly connected to waking-life activities, while late-night dreams are more emotional, important, varied in time orientation, and hyperassociative. These differences align with known sleep-stage functions: non-REM sleep supports episodic memory consolidation and REM sleep supports emotional regulation and creativity. The findings suggest that dream content reflects underlying sleep processes such as memory consolidation, emotion-processing, and creativity across the night.