UC Davis

We investigated the relationship between length and dreamlike quality in sleep mentation reports. Reports were obtained by waking subjects at sleep onset (SO) and at 5 and 10 minutes into the second (REMP2) and fourth REM periods (REMP4). Reports were recorded, transcribed, and scored blindly for total word count (TWC) and dreamlike quality as measured by a composite dream scale score (CDS). Dreamlike quality was strongly correlated with TWC; both CDS and TWC scores increased across successively later awakenings. Significant differences were found in both TWC and CDS between SO and REMP4 and also between REMP2 and REMP4; however, differences were not significant between SO and REMP2 or between the 5 and 10 minute awakenings in REMPs 2 and 4. These findings provide further evidence that the amount of dreamlike mentation is related to the within-sleep arousal level rather than to REMP duration and that the dreamlike quality of reports increases as they become longer.