Sensations are unlike and unusual other common sensations, those with RLS have hard time describing them. Peoples use the words as, electrical, uncomfortable, painful, creeping, needles, pins, itching, pulling, ants inside legs and legs. Sensation and urge can occur in the body part, but most cited location is legs then arms. Some people have no or little sensation, and still have strong urge to move, while, RLS suffers may unable to qualify sensations to non-suffers.

Most research on disease mechanism of RLS has focused on iron and dopamine system. Such hypotheses are based on observation that iron and levodopa can be used to treat restless legs syndrome, and also on finding from the functional brain imaging, autopsy series and animal experiments.

The most common associated medical condition is deficiency of iron that accounts for just over 20% of RLS cases.

In other associated conditions with RLS include venous reflux or varicose vein, folate deficiency, uremia, sleep apnea, peripheral neuropathy, thyroid disease and auto-immune disorders such as Sjogren syndrome, rheumatoid arthritis and celiac disease. Both secondary and primary RLS can worsen by the surgery, however, injury or back surgery can be associated with RLS causing. Many experts believe that restless legs syndrome and periodic limb movement disorders are associated strongly with ADHD in children.