Periodic limb movement disorder (PLMD)

As suggested by its name, PLMD is an involuntary movement disorder. (An older name, nocturnal myoclonus, is rarely used anymore.) People with this problem experience sudden, involuntary leg movements during the night, such as kicking or jerking. The difference between this and restless leg syndrome is that, unless the kicking wakes you up, you don't know you're doing it. You don't experience the tingling and discomfort that leads you to consciously move your legs, as with restless leg syndrome. At least 80 percent of people with restless leg syndrome have PLMD, but the reverse isn't true.

What to do: See a doctor, who will likely first check you for underlying conditions related to PLMD. Diabetes, thyroid disorders, anemia, and a number of other conditions can cause PLMD. If you do have another condition, the doctor will treat it and see if the PLMD goes away. The next step is to control the involuntary movements with medication. Drugs that suppress muscle contractions work well for preventing PLMD. The doctor may also prescribe medication to help you sleep more deeply, with the idea of preventing the involuntary movements from keeping you in light sleep.