Disclaimer: I don't know how much restless the leg has to be, in order to be considered a syndrome.
RLS runs not only in my family but also several people in the locality. My hypothesis is that RLS is a genetic/epigenetic adaptation to prevent mosquitoes or other insects from sucking blood. I, indeed, live in a malaria zone. I don't know enough biology to device a scientific experiment to prove my hypothesis.
Is there any scientific research done in this field? Someone who is well versed in this field should try it.
