On the other hand, some disadvantages still exist since the diagnostic criteria for RLS are subjective, some more objective and reliable diagnostic criteria need to be brought up for a further diagnosis and classification of RLS, such as biological markers, genetic features, PLMS measuring, polysomnography, and actigraphy changes. Some new tools are to be developed for standardize case ascertainment (Allen et al., 2014). A case-control study in Germany reveals that inositol metabolites increased specifically in RLS patients (Schulte et al., 2016). This might be a discovery approach using serum metabolite profiling in RLS.