Periodic limb movement disorder

Periodic limb movement disorder (PLMD), previously known as nocturnal myoclonus, is a sleep disorder where the patient moves limbs involuntarily during sleep, and has symptoms or problems related to the movement.

PLMD should not be confused with restless leg syndrome (RLS). RLS occurs while awake as well as when asleep, and when awake, there is a voluntary response to an uncomfortable feeling in the legs. PLMD on the other hand is involuntary, and the patient is often unaware of these movements altogether.