an acronym for Periodic Limb Movement Disorder; a condition in which the legs or arms twitch or move involuntarily and periodically during sleep.

Periodic Limb Movement Disorder. A disorder in which rhythmic jerking of the legs interrupts sleep, causing insomnia and/or excessive daytime sleepiness.

Periodic Limb Movement Disorder. This disorder involves periodic episodes of repetitive movements, usually in the legs, that occur about every 20 to 40 seconds. The movements may appear as brief muscle twitches, jerking movements or an upward flexing of the feet. The movements occur in clusters, lasting from a few minutes to a few hours. Most children with PLMD are not aware of the movements. PLMD can result in frequent brief arousals throughout the night, leading to daytime sleepiness.