Slow wave and REM sleep mentation.

The aim of this experiment was to compare the characteristics of mental activity during REM and Slow Wave Sleep (SWS). Forty dream reports and their mnemonic associations were collected from twenty subjects. The reports were analyzed for structure (number of temporal units, number of report multi-units, and narrative continuity), awareness (reality testing, subjective time), and content (self, setting, laboratory references, number of non-self characters, implausibility, body feelings, number and intensity of emotions, vividness). Associations were classified as episodic and semantic memories. Results showed that REM reports were significantly longer than SWS reports. Minor content SWS-REM differences were also detected, which were more quantitative than qualitative. The collected observations might support the tentative hypothesis that dreaming is a continuous process, which is not unique to REM sleep. Different levels of engagement of the cognitive system are responsible for the SWS-REM differences that were detected.