A graph theory approach to chart the architecture of dream and mind-wandering reports

The language people use to describe their inner experiences arising during sleep and wakefulness provides a window into the mind. Dreams and unguided waking thought, here referred to as mind wandering, are thought to reflect unique individual differences and mental health. Here we use graph theory to analyse a large dataset of dream (n = 1434) and mind wandering (n = 1619) reports from 176 individuals. We found that dream reports have a more complex structure, while mind-wandering reports have fewer word repetitions and are more verbose, with essential transition points in the structure of the texts. Dream reports, which rely on recall over longer periods of time, tend to have more word repetitions, local cliques, and global integration, comparatively indicating a small world structure. Capitalising on a repeated measures design, we found that the structure of dream and mind-wandering reports contains individual-specific information. Finally, we observed that word centrality (i.e., lower lexical diversity) in dream and mind-wandering reports is predictive of depression and anxiety symptoms, respectively. Thus, this approach is sensitive to individual differences, quantitatively differentiates reports of two different states of consciousness, and seems promising for cost-effective analyses of large naturalistically occurring qualitative datasets.