Restless Legs Syndrome (RLS) Make an Appointment Find a Doctor Ask a Question Reviewed by Dr. Harrington, Sheila Tsai, MD (March 01, 2017) People with restless legs syndrome (RLS) experience an uncomfortable feeling in the legs, coupled with a strong urge to move the legs so as to alleviate the symptoms. The feeling may be described as "creeping," "crawling" or "aching" and happens most often at night, during periods of rest or inactivity. Some people with RLS have trouble falling asleep. They may also wake up frequently at night because of periodic limb movements, a condition that occurs frequently among people with RLS. Periodic limb movement disorder (PLMD) is characterized by repeated leg movements. Unlike RLS, which occurs when a person is resting or trying to fall asleep, the movements of periodic limb movement disorder occur during sleep, and the person may be unaware of them. These movements may occur in the toes, feet, ankles and/or legs. According to some estimates, as much as 15 percent of the population has RLS. Most have symptoms that are mild and can be managed with self-care and better sleep habits. For more severe cases, medications may help. More women are affected than men. RLS is more common in people with anemia or kidney problems and who are pregnant. Causes Restless legs syndrome is a neurological disorder, thought to be related to the activity of dopamine, a chemical that carries messages in the central nervous system. RLS can also be caused by other conditions, such as peripheral neuropathy or diabetes. Iron deficiency can cause RLS or make it worse. Risk factors About half of people with restless legs syndrome have relatives with the condition. Although symptoms can start at any age, older people may be more likely to have severe symptoms. RLS is more common during pregnancy. It may also appear in people who have another medical problem, such as anemia or kidney problems. National Jewish Health experts provided information on this topic for use on the U.S. News & World Report website. Programs & Services Sleep Center Clinical Trials For more than 100 years, National Jewish Health has been committed to finding new treatments and cures for diseases. Search our clinical trials.