We made a polygraphic study of 6 patients with nocturnal paroxysmal dystonia (NPD) in which the cyclic alternating pattern (CAP) parameters were compared with those of a group of age- and sex-matched controls.All patients met the requirements for NPD diagnosis, characterized by generalized stereotyped movements (dystonic-dyskinetic), with a 1-min centered duration but with no clear evidence of epileptic abnormalities in the waking EEG and during nocturnal recordings.Besides the major events, the NPD polysomnograms also showed shorter, repeated episodes of shorter duration (generally