Sleep complaints in periodic paralyses: a web survey

Neuronal potassium conductance has been shown to influence the sleep-wake cycle and REM sleep homeostasis. The periodic paralyses (PP) are characterized by episodes of muscular weakness associated with changes in serum potassium levels and, therefore, with possible alterations in extracellular neuronal potassium conductance. We submitted a sleep questionnaire to the members of Periodic Paralysis International Listserv, an on-line support and information group for subjects with PP. Three control groups were made up of patients with untreated depression, patients with depression under treatment and healthy subjects. Both subjects with PP and those with untreated depression had a higher frequency of self-reported insufficient sleep quality and a higher number of nocturnal awakenings than patients with depression under treatment and healthy controls. PP subjects had more self-reported daytime sleepiness, sleep-related hallucinations and nightmares/abnormal dreams than the other three groups. Patients affected by PP may have disrupted sleep architecture and homeostasis. In particular, we suggest that the stereotypical abnormal dreams reported by several patients may reflect oneiric elaboration of nocturnal episodes of flaccid paralysis, while the increased frequency of sleep-related hallucinations may be due to enhanced REM sleep expression associated with alterations of neuronal potassium conductance.