Melatonin and Restless leg syndrome - a study from FDA data
Summary:
Restless leg syndrome is found among people who take Melatonin, especially for people who are female, 60+ old , have been taking the drug for < 1 month, also take medication Vitamin D3, and have Narcolepsy. This study is created by eHealthMe based on reports of 19,565 people who have side effects when taking Melatonin from Food and Drug Administration (FDA), and is updated regularly.

Some drugs and medications have been associated with restless leg syndrome including: caffeine, alcohol, H2-histamine blockers (such as ranitidine [Zantac] and cimetidine [Tagamet]), and certain antidepressants (such as amitriptyline [Elavil, Endep]).