Restless legs syndrome is a sleep disorder in which a person experiences unpleasant sensations in the legs. People who have this disorder often describe the sensations as creeping, crawling, tingling, pulling, or painful feelings in the calves, although the entire leg can be affected. These sensations can occur when the person lies down or sits for long periods, such as in bed, at a desk, or riding in a car. Moving, rubbing, or massaging the legs brings relief, at least briefly. People with restless legs syndrome find it difficult to relax and fall asleep, often sleeping best during the morning hours. A lack of sufficient sleep at night causes daytime drowsiness and affects performance at home and at work. Many people with restless legs syndrome have periodic limb movement, which is characterized by involuntary jerking or bending leg movements that occur every 10 to 60 seconds during sleep.

The cause of restless legs syndrome remains unknown, but certain factors have been linked to the disorder. They include a family history of the disorder; pregnancy; low levels of iron in the blood; diseases such as kidney failure, diabetes, and rheumatoid arthritis; and a high caffeine intake.
Both men and women can develop restless legs syndrome, which is more common and more severe among older people. An accurate diagnosis often depends on how well the person can describe his or her symptoms because there is no visible abnormality in the legs and there is no diagnostic test to detect the disorder. Mild cases of restless legs syndrome respond well to self-treatments such as taking a hot bath, massaging the legs, using a heating pad or an ice pack, exercising, and eliminating caffeine. More serious cases are treated with benzodiazepines (such as clonazepam or diazepam) and opioids (such as codeine or propoxyphene). These drugs do not cure restless legs syndrome but only treat the symptoms. Some people respond well to a nondrug treatment called transcutaneous electric nerve stimulation (TENS), in which electrical stimulation is applied to the legs or feet for 15 to 30 minutes before bed to reduce leg jerking during sleep.