Disorders of arousal and sleep-related hypermotor epilepsy are interrelated. Some new viewpoints.

NREM parasomnias overlap with sleep-related hypermotor epilepsies in multiple ways. Both conditions are characterized by fragmented sleep; share symptomatic features; have family-, and population-genetic relationships; and NREM parasomnia-episodes are underlain by sleep-wake dissociation likely featuring SHE seizures as well. Most importantly, the two conditions have very similar links with NREM sleep's high homeostatic pressure periods closely related to sleep microstructure including sleep-like micro-arousals, the dynamics of cyclic alternating pattern A1 and slow wave bistability. While the unquestionable distinction of the two conditions, epileptic and non-epileptic, is essential both theoretically and practically; their striking relationship calls for explanation.