Are there many differences between REM and NREM dream reports?

Although there were indications in early laboratory studies that dreaming occurs almost exclusively in REM sleep and that there were difference in the content of REM and NREM reports, many later studies suggest that the differences in recall are not black and white, especially late in the sleep period, and that some but not all of the content differences disappear when there is a control for word length (i.e., the number of words used to describe a given dream). Still, most studies conclude that dreams are more frequent and longer during REM periods and that many NREM reports seem to be “thoughts,” not dreams. In fact, NREM reports are more often a continuation of waking thoughts and memories, whereas there are few episodic memories in REM or home dream reports.

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