In which sleep phase does most dreaming occur?

Most dreaming occurs during REM sleep, which stands for Rapid Eye Movement sleep. This phase is characterized by increased brain activity, which resembles that of wakefulness, and is when the body experiences physiological changes such as rapid eye movements and increased heart rate. The enhanced brain activity during REM sleep facilitates vivid dreaming, which can range from fantastical to realistic scenarios. This phase typically occurs multiple times throughout the night, with longer periods of REM sleep occurring in later cycles, allowing for a rich tapestry of dreams.

In contrast, slow-wave sleep and non-REM sleep involve different levels of brain activity, primarily focused on physical restoration and memory consolidation rather than vivid dreaming. Transitional sleep, while a brief phase occurring between wakefulness and sleep or between sleep stages, does not typically contribute to the dreaming experience as prominently as REM sleep does. Thus, REM sleep is distinctly recognized as the phase where most, if not all, significant dreaming takes place.