Periodic Limb Movement Disorder (PLMD) is related to Restless Legs Syndrome but occurs during sleep rather than while awake. These periodic, rhythmic movements may occur in the arms or legs but are more prevalent in the legs. Many times the bed partner describes this as a jerk that occurs over and over during the night. This is not to be confused with a "hypnic jerk" or sudden movement that occurs with many people at sleep onset. PLMD movements occur primarily in the early part of the night. These movements may cause the person to have awakenings during the night, which then results in daytime sleepiness.
What causes PLMD?
The same factors associated with Restless Legs Syndrome (RLS) apply to PLMD. About 30% of the cases appear to be genetically linked. However, 70% of the cases there is no known cause. Some symptoms related to PLMD are: iron deficiency, anemia, and poor blood circulation in the legs, kidney disorders, alcoholism and some vitamin deficiencies. Sometimes people with narcolepsy have PLMD. Many times people with RLS will have PLMD as well.
Many times people with PLMD sleep through their movements and do not require any treatment at all. Sometimes these people need to work on the soundness of their sleep by improving their sleep hygiene. If the PLMD is disturbing the sleep then a prescription medication may be given.