Lucid Dreaming Frequency Associated With Grey–White Matter Networks: An Exploratory Multimodal <scp>MRI</scp> Study

Lucid dreaming, defined as the experience of becoming aware of dreaming while dreaming, offers a unique window into a state of consciousness characterised by a blending of the sensory vividness of REM sleep with the self-awareness of wakefulness. While past functional imaging has shed light on the neural activity supporting lucid dreaming, the structural brain correlates of lucid dream frequency as an individual trait varying in the normal population, remain largely unexplored. Moreover, the possibility of separating ordinary dreams from lucid dreaming has been only partially explored. In this exploratory study, we employed a data-driven, multimodal neuroimaging approach known as mCCA + jICA, to identify joint and modality-specific grey matter (GM) and white matter (WM) morphometric features associated with the individual differences in lucid and non-lucid dream recall measured by a validated self-report measure. Results revealed that lucid dreaming frequency was associated with one joint GM-WM component, encompassing frontal, temporal, parietal, and cerebellar regions implicated in metacognition, imagery, and volitional control, as well as one GM-specific component involving visual and attentional areas including the cuneus. In contrast, ordinary dream recall frequency was associated exclusively with two WM-specific components, showing no overlap with those linked to lucid dreaming. These findings suggest that the tendency to experience lucid dreams is rooted in distributed, structurally covarying brain systems, distinct from those underlying general dream recall. The presence of joint components supports the view that lucid dreaming depends on the integration of cortical and subcortical systems mediating self-awareness and internal simulation.