Temporal sequence and unit composition in dream reports from different stages of sleep.

Mentation reports were collected from 23 subjects following awakenings from REM and NREM sleep and at sleep onset. Subjects organized these reports according to temporal sequence, and judges scored them for activity-based temporal units and for the composition of such units. The judgment data were subjected to analysis to determine whether reports differed systematically by state in either thematic sequencing (moment-to-moment setting and character continuity) or unit composition (density of characterization, setting articulation). Previous findings of inter-state differences in dream quantity (recall, length) were replicated. a sample of typical-length multiunit reports showed a number of stage differences, while samples of matched-length reports did not differ by stage in thematic sequence or the degree of articulation of single units. However, matched for length, REM reports continued to contain more per-unit self representation than did sleep onset reports and denser per-unit overall characterization than NREM reports. The results suggest that most inter-stage differences in dream "quality" are, in fact, by-products of inter-stage differences in dream quantity, but that there are residual stage differences that can coherently be attributed neither to differences in the continuity with which dream production processes are activated in different stages nor to differences in dream retrieval from different stages.