Background Restless leg syndrome (RLS) is a type of sensorimotor disorder, and clinical workers have made some recent developments in its pathological mechanism and treatment. Epidemiological studies have verified that RLS is notably associated with neuro-psychological diseases, kidney disease, cerebro-cardiovascular diseases, nutritional and metabolic diseases, and pregnancy disorders. The diagnostic rate of RLS is low due to lack of specific clinical symptoms, clear genetic and biological markers, and polysomnography (PSG) diagnostic criteria. There are several sleep centers in foreign countries where the suggested immobilization test (SIT) has been applied in clinical treatment and research about RLS. Objective To evaluate the clinical significance of SIT in RLS diagnosis. Methods The study enrolled 220 patients who visited the PKU-UPenn Sleep Center, Peking University International Hospital with a main complaint of discomfort in bilateral lower limbs during daytime rest or before sleep, and 150 healthy vo