Dream recall and sleep duration: state or trait factor.

Previous research regarding the relationship between habitual sleep duration and frequency of dream recall yielded conflicting results, whereas experimental manipulation of sleep duration showed a significant effect on dream recall. In this study analyzing both effects simultaneously, the findings from diaries kept by the 196 participants over 28 to 111 days indicated that intra-individual fluctuations in sleep duration were significantly related to dream recall whereas interindividual differences in dream recall were not associated with differences in sleep duration. Sleep inertia might be an explanation for this finding.