Test Your Knowledge

Periodic limb movement disorder (PLMD) causes patients to move their legs and arms during sleep. Movements are most likely to occur during the non-REM (rapid eye movement) sleep, which occurs early in the patient’s sleep period.

PLMD-related movements range from flexing a joint to flailing the arms and legs. A characteristic movement is the upward extension of the big toe every 20 to 40 seconds over a period of a few minutes to several hours. How often the movement occurs may differ, with estimates ranging from every 10 to 60 seconds. These movements may also be accompanied by flexing of the ankle, knee or hip. A patient’s legs may uncontrollably twitch, jerk or kick while asleep. In some patients, the arms are also involved. The amount of movement typically varies from night to night.

Patients with PLMD are often unaware of their movements. In some cases, the movement causes the patient to awaken, but in many it only causes semi-arousal. This can lead to limited rest at night and daytime sleepiness and fatigue.