Symposium: Normal and abnormal REM sleep regulation: Dreaming and REM sleep.

The discovery, 40 years ago, of REM sleep and of its putative association with dreaming in the adult human raised the possibility that neuroscientific investigations of REM-sleep physiology would someday 'explain' the distinctive features of dream experience. I argue here against the possibility, since replicated psychological data demonstrate that REM sleep is neither a necessary nor a sufficient condition for dreaming to occur. Dreaming depends, rather, upon the possession of conscious representational intelligence in conjunction with any psychophysiological state in which ideation is being driven neither volitionally nor by external stimulation.