**3. RLS prevalence**

RLS has been mainly studied in North America and Europe and appears to have a prevalence of 5 to 15% with up to a 2:1 female ratio (Berger K et al., 2004, Phillips B et al., 2000). Prevalence is markedly higher in certain groups such as Icelandic women where RLS prevalence was found to be 24.4% (Benediktsdottir B et al., 2010). Of interest, the increased risk of RLS in women appears to be linked to parity with an increased risk of RLS directly proportional to the number of children (Berger K et al. 2004). In contrast, nulliparous women have the identical risk of RLS as men the same age. While, most of the epidemiology of RLS has been researched in Europe and North America, there are studies from other areas. Research from Asia appear to yield lower prevalence rates. (Chen NH et al., 2010). Overall, the prevalence of RLS appears to be higher in North American/European populations, especially in women.
