A nocturnal episode characterized by disorientation, grogginess, and, at times, substantial agitation upon awakening from slow-wave sleep or following forced awakenings. These characteristics might present as agitation, crying or moaning, disorientation, and particularly slow mentation on arousal from sleep (i.e., sleep inertia). The duration of episodes is typically 5 to 15 min but they might last up to several hours. [ PMID:27647645 ]