For most people with restless legs syndrome (RLS), the disorder doesn’t strike on its own. It often has a partner in crime called periodic limb movement of sleep (PLMS). In fact, about 80% of people with RLS also have PLMS. PLMS tends to affect older adults and, like RLS, degrade restorative sleep quality. With PLMS, you may experience uncontrollable twitching or jerking movements in your legs while you’re trying to sleep. Less commonly, these movements can affect the arms as well. The movements may occur as often as every 15 to 40 seconds and may last all night long. So it’s no surprise that PLMS can keep you awake at night. The exact cause of PLMS isn’t yet known. However, many underlying medical conditions that cause RLS, such as anemia, kidney disorders, and iron deficiency, may play a role in PLMS as well. People who have PLMS aren’t always aware of it, but their spouse or partner often notices the disturbance. Be sure to tell your doctor if you think you may have PLMS. Certain medications that treat RLS may also help with PLMS. Self-care techniques such as yoga, meditation, a hot bath, or leg massage may help as well.