Do individuals with disorders of consciousness dream and mind wander? Implications for improving diagnosis and understanding patient wellbeing.

Fluctuations in the presence, experiential quality and contents of consciousness occur naturally during sleep and wakefulness and are core features of the healthy human mind. The purpose of this article is to consider the possibility that such fluctuations, including mind wandering and dreaming, which we refer to collectively as spontaneous thoughts and experiences (STE), may also be important elements of experience in certain patients with disorders of consciousness (DoC). The presence of these states may have urgent implications for DoC diagnosis, which centres on the detection of consciousness. Furthermore, learning more about STE in DoC may provide insight into subjective experience and quality of life in DoC, about which little is currently known. Given the challenges that exist in studying conscious experience in this population, much of the evidence about STE we consider is indirect and involves triangulation from the healthy population and other brain-injured patients. The evidence we consider is inconclusive, but it indicates that the occurrence of mind wandering and dreaming in DoC is a real possibility that, because of its important implications in these patients, requires further research. We argue that, given the possible life-or-death consequences of diagnosis in DoC, it is of pressing importance to use diagnostic measures that are sensitive to these internally directed forms of conscious experience. We also consider some lines of research that may deepen our understanding of STE in DoC, and how further knowledge about these states may impact inferences about quality of life in this population.