I picked up this link from rls.org forum.
eurekalert.org/pub_releases...
Very little detail but it raises the whole adenosine/caffeine issue again. It could perhaps identify why it is that some people find a cup of coffee helps when their rls kicks off. It's a tricky area. I have tried dipyridamole (which affects adenosine) for my rls. I'm not sure that it provided much relief to the actual symptoms but I almost immediately felt better when taking it - much less tired and more 'myself'.