Periodic limb movement disorder was previously known as sleep myoclonus or nocturnal myoclonus. The hallmark of this condition is repeated lower extremity movements during non-REM sleep. These frequent limb movements may occur every 5 to 90 seconds. Naturally, this causes a disruption of sleep and patients feel exhausted during the day. It is common that patients are not aware of limb movements and do not realize that they have a sleeping disorder.