Beyond the REM--NREM Dichotomy: A Multidimensional Approach to Understanding Dreaming

Traditionally, dream research focuses on accounting for typical psychological features of dream experiences characteristic of different sleep stages in terms of the global physiological features of the sleep stages in question. However, as subtle differences got into the forefront of enquiry, as, for example, in questions concerning between-stage similarities and within-stage differences of mentations, this methodology became insufficient. What recent findings and theoretical developments suggest is that understanding mental activity during sleep requires studying the fine-grained characteristics of the phenomenal features of individual dreams, which, in turn, demands identifying specific neural processes that might underlie different characteristics of the experiences, and tracking their changes not just between but also within standard sleep stages. The paper argues that such a shift of focus from describing global stages to understanding the significance of local changes results in a true paradigm shift in dream research that can break away from the tradition of thinking about sleep mentation in terms of discrete categories (e.g. REM/ NREM, or high/low global activity level), and offers a novel way of looking at dreams (and other conscious experiences) as forming a multidimensional continuum.