The Physiology and Functions of Dreaming

Dreams are dynamic mental phenomena that reflect core processes of emotional regulation, memory integration, and cognitive restructuring during sleep. Since the discovery of rapid eye movement (REM) sleep in 1953, scientific exploration has deepened our understanding of how different sleep stages contribute to dreaming. REM sleep, in particular, is associated with vivid and emotionally charged dreams due to increased activation in limbic structures such as the amygdala, alongside decreased prefrontal regulation. Non-REM (NREM) dreams tend to be more fragmented and related to recent experiences, playing a complementary role in declarative memory consolidation. This review outlines the conceptual and historical evolution of dream research, examines neurophysiological mechanisms across REM and NREM sleep, and highlights the central role of emotion processing within dream content. Emotional experiences in dreams may aid in resolving psychological conflicts, reinforcing affective memories, and supporting intuitive decision-making. While various dream forms―such as lucid dreaming, daydreaming, precognitive dreams, and conception dreams―demonstrate the diversity of dreaming phenomena, their psychological relevance is best understood within the broader framework of affective neuroscience. Further interdisciplinary research is needed to clarify the clinical and cognitive significance of dreaming, particularly its implications for emotional well-being and mental health.