I had this condition for a while. As mofaha notes, the syndrome involves uncomfortable muscular sensations coupled with an overwhelming desire to move one's legs; I generally described it by saying that my legs wanted to get up and go running even though the rest of me really wanted to go to sleep. Obviously, there are far worse diseases out there, but the syndrome does make life uncomfortable for the sufferer (and for anyone with whom he is sharing a bed).

Although the causes of restless-legs syndrome are unclear, there are a few treatments. Painkillers do work, especially if they contain a mild sleeping drug (like Tylenol PM). Doctors will sometimes prescribe benzodiazepines such as Restoril for more serious cases. Before resorting to drugs, though (especially habit-forming drugs whose effects decline over time) it's good to try some non-pharmacological approaches. Stretches, relaxation exercises, and massage can provide some relief; these helped me a little, but not much. It's often easier and more effective to eliminate some factors that may worsen the condition. For example, my syndrome went away entirely after I drastically reduced my intake of caffeine. These days, I don't consume any caffeinated drink within 12 hours of bedtime; I only have a problem if I forget and have some chocolate or a Coke at dinner.

("Go without caffeine?" you say. "You must be crazy! Wasn't it hard to give it up?") Yeah, but I can actually sleep through the night now, which means that I don't need caffeine to stay awake during the day. A blessing for the doctor who suggested that to me (and a pox on the doctor who recommended that I take a Valium every night for the rest of my life).