Dreaming and the brain: Toward a cognitive neuroscience of conscious states

Sleep researchers in different disciplines disagree about how fully dreamin g can be explained in terms of brain physiology. Debate has focused on whet her REM sleep dreaming is qualitatively different from nonREM (NREM) sleep and waking. A review of psychophysiological studies shows clear quantitativ e differences between REM and NREM mentation and between REM and waking men tation. Recent neuroimaging and neurophysiological studies also differentia te REM, NREM, and waking in features with phenomenological implications. Bo th evidence and theory suggest that there are isomorphisms between the phen omenology and the physiology of dreams. We present a three-dimensional mode l with specific examples from normally and abnormally, changing conscious s tates.