Sleep paralysis in narcolepsy: more than just a motor dissociative phenomenon?

Sleep paralyses are viewed as pure motor phenomena featured by a dissociated state in which REM-related muscle atonia coexists with a wakefulness state of full consciousness. We present a 59-year-old man diagnosed with narcolepsy experiencing sleep paralysis, who failed to establish the boundaries between real experience and dream mentation during the paralysis: the patient's recall was indeed featured by uncertainty between real/unreal and awaken/dreaming. Hereby, we suggest that sleep paralysis may represent a more complex condition encompassing a dissociated state of mind together with the dissociative motor component. Neurophysiological data (spectral EEG analysis corroborated by cross-correlation analysis) reinforce the idea that the patient was in an intermediate state of mind between wake and REM sleep during the paralysis. The persistence of local impaired activity proper of REM sleep in cortical circuits necessary for self-reflective awareness and insight, in conflict with wakefulness-related activation of the remaining brain areas, could account for disrupted processing of afferent inputs in our patient, representing the underlying pathophysiologic substrate for patient's failure to establish the boundaries between real experience and dream mentation.