Dream report length is more dependent on arousal level than prior REM duration.
Brain Research Bulletin January 1, 1994 N Rosenlicht, T Maloney, I Feinberg
Twenty-two young adults were awakened during REM sleep to test whether the length of prior REM sleep affects dream recall. Participants were awakened after either 5 or 10 minutes of REM sleep during the second and fourth REM periods of the night. The number of words used to describe dream mentation did not differ between 5- and 10-minute awakenings. However, reports from the fourth REM period contained nearly twice as many words as those from the second REM period. The findings suggest that recall from REM awakenings depends on central arousal level and its influence on memory processes.