Restless legs syndrome (RLS) is a disorder characterized by unpleasant sensations in the legs and a strong urge to move them. RLS may also cause jerky leg movements every 20 to 30 seconds throughout the night. Sometimes RLS can affect other parts of the body, too. RLS symptoms may occur or get worse while you’re at rest or sleeping. Because the symptoms are usually worse at night, they can greatly interrupt your sleep and lead to sleepiness when you need to be awake. RLS can be so bad it is mistaken for insomnia.