Hypnic jerks are an underestimated sleep motor phenomenon in patients with parkinsonism. a video-polysomnographic and neurophysiological study

Highlights • Hypnic jerks are a frequent and constant video-polysomnographic finding in patients with parkinsonism. • Hypnic jerks in parkinsonism patients seem to appear early in the disease course. • Detailed neurophysiological analysis does not show any recurring, ordered propagation pattern of muscle activity during hypnic jerks. • Hypnic jerks share the same random motor activation and propagation pattern in both healthy subjects and in patients with parkinsonism. • The lack of any ordered propagation of the spreading of muscular contraction suggests a subcortical origin of the jerks, confirming our previous findings in a healthy patient.