Restless legs syndrome (RLS), also known as Willis–Ekbom disease (WED), is a common neurosensorimotor disorder. The clinical importance of RLS/WED is underlined by epidemiological studies showing that one in 100 people may experience RLS/WED symptoms which seriously impact quality of life . The diagnosis is based primarily on patient self-report and history. However, a number of diseases have symptoms that are often confused with those of RLS/WED, and other conditions are associated with higher rates of RLS/WED .The formal diagnostic criteria for the Restless Legs Syndrome (RLS) start with the seminal monograph Restless Legs by Karl-Axel Ekbom in 1945 . In 1960, he offered the following diagnostic guidance: The following criteria should be born in mind. The sensations appear only when the patient is at rest, most often in the evening and early part of the night, and produce an irresistible need to keep the legs moving. Furthermore, the sensations are not felt in the skin but deep down inside the legs . In 1990, the American Sleep Disorder Association published the InternationalClassification of Sleep Disorders (ICSD) and described the first official operational diagnostic criteria for RLS/WED. The ICSD classified RLS/WED as one of the “Intrinsic Sleep Disorders” under the subgroup of “dyssomnias” and defined RLS/WED by “disagreeable leg sensations, usually prior to sleep onset, that causes an almost irresistible urge to move the legs” (Table 1.1).