Both sensory and motor symptoms show significant circadian rhythm in RLS, which display as a peak at similar time at night. A study showed the increase in melatonin secretion to be the only changes preceding the sensory and motor symptoms in RLS patients, indicating melatonin might affect the symptoms by its inhibitory effect on dopamine secretion in central nervous system (Michaud et al., 2004). The intensity of RLS symptoms peaks on the falling phase of the core body temperature, another endogenous marker of circadian rhythm, while it decreases when core temperature increases (Hening et al., 1999; Barriere et al., 2005).