Sleep-Related Movement Disorders: Hypnic Jerks

Purpose of ReviewHypnic jerks represent a benign physiological phenomenon of sleep, which must be differentiated from other sleep-related movement disorders and epilepsy. A comprehensive review of hypnic jerks is presented with emphasis on recognition, physiology, evaluation, and treatment.Recent FindingsThe recent edition of the International Classification of Sleep Disorders (ICSD-3) has classified hypnic jerks as a sleep-related movement disorder under the subheading isolated symptoms and normal variants. Although generally benign, there have been increasing reports of excessive hypnic jerks in neurological disorders such as Parkinsonism, migraine, and brainstem lesions and children with neurologic disorders. Recent research identifying changes in the polysomnogram has led to a better understanding of the physiology of hypnic jerks. A variety of different motor patterns have been described; however, the origin and physiology of hypnic jerks remain enigmatic.SummaryHypnic jerks represent a fascinating phenomenon of sleep; however, additional studies are needed to clarify their physiology and origin.