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Periodic limb movements in sleep (polysomnogram)

Periodic limb movements are repetitive movements of the legs, sometimes of the arms, occurring at 5- to 90-second intervals, often associated with arousals that reduce the quality of nocturnal sleep. The figure shows periodic limb movements on polysomnogram. C3-A1, C4-A2, and O1-O2 = electroencephalogram channels; L EOG and R EOG = electrooculogram channels; EMG Subm. and EMG Tib. = electromyogram channels to record submental and tibialis muscle activity; Oral/Nasal = air flow; Chest = thoracic excursions; Abd. = abdominal movements; Oxim. = hemoglobin saturation of oxygen. (Contributed by Dr. Antonio Culebras.)