Abstract
The purpose of this study is to construct a rating scale, which measures dream properties, excludes extraneous variables caused by experimenter and/or subject, and reflects physiological activation during sleep. We selected 52 adjective items for the rating scale, expecting to reflect the four hypothetical properties of dreaming. We conducted polysomnographic studies employing REM periods awakening technique to 34 graduate or undergraduate students and obtained a total of 318 responses to the questionnaire. Promax rotation of the factor analysis were repeated by changing the number of the items and the factors. Finally, four factors (bizarreness, evaluation, impression, and activity) were extracted from 15 items. All items had more than .68 factor loading to one of the factors. By using a total of raw scores for each factor, we calculated the mean and the SD for standardization. The normalized DP scale demonstrated high reliability. Correlation between each score of the DP scale and physiological variables, such as atonia, REMs, twitching, body movement, and NREM-REM sleep cycle, suggested a validity of the DP scale. In particular, the impression and the activity related to the atonia index and the REMs density which reflected REM sleep activation system of the brainstem.
