What Is Periodic Limb Movement Disorder?
More than 80 percent of people with restless legs syndrome also experience a more common condition known as Periodic Limb Movement Disorder (PLMD).
Periodic limb movement disorder is characterized by involuntary leg twitching or jerking movements during sleep that typically occur every 10 to 60 seconds, sometimes throughout the night. The symptoms cause repeated awakening and severely disrupted sleep.
Movements Caused by Periodic Limb Movement Disorder Are Involuntary
Unlike restless legs syndrome, the movements caused by periodic limb movement disorder are involuntary (people have no control over them). Although many patients with restless legs syndrome also develop periodic limb movement disorder, most people with periodic limb movement disorder do not experience restless legs syndrome.
Like restless legs syndrome, the cause of periodic limb movement disorder is also unknown.
Who Is Most Affected by Restless Legs Syndrome?
Restless legs syndrome occurs in both genders, although the incidence may be slightly higher in women. Although restless legs syndrome may begin at any age, even as early as infancy, most patients who are severely affected are middle-aged or older. In addition, the severity of the disorder appears to increase with age. Older patients experience symptoms more frequently and for longer periods of time.