Rhythmic alternating patterns of brain activity distinguish rapid eye movement sleep from other states of consciousness.
Proceedings of the National Academy of Sciences of the United States of America June 18, 2013 Ho Ming Chow, Silvina G. Horovitz, Walter S. Carr et al.
REM sleep is a distinct state of consciousness with brain activity levels similar to wakefulness but radically different conscious awareness. Using fMRI, researchers observed that the default mode network (DMN), which reflects level of consciousness, becomes functionally uncoupled during deep sleep but recouples during REM sleep, resembling wakefulness. Unlike deep sleep or wakefulness, REM shows widespread, temporally dynamic interactions between unimodal sensorimotor areas and higher-order association cortices, including the DMN. These two systems become anticorrelated and fluctuate rhythmically in alternating multisecond epochs at 0.1 to 0.01 Hz, suggesting a model relevant to dream formation and memory consolidation.