What causes restless legs syndrome? Why do so many people have it?

Do kids get RLS? Why do children get RLS? Listen to this on NPR JR

When Brain Shuts Down, Legs Kick into Overdrive

 by David Kestenbaum

It's maddening to have a feeling that you can't explain. When I was a kid on long car rides, I would sometimes experience a strange sensation in my legs. I felt like I had to move my legs. When I did, the feeling would go away for a few seconds but then come back.

It struck at the worst times — my legs kept me awake when I was tired and needed to sleep. As an adult, the feeling periodically comes back to haunt me, during a slow movie, on airplane rides, or having a late drink at a bar...

I had no idea what this was until a few years ago when I found a Web site about something called Restless Legs Syndrome (RLS). I had that eureka moment people must have when they find out that what ails them has a name. "Yes!" I thought, "THIS IS WHAT I HAVE!"

My case is fairly tame. People with severe forms of Restless Legs Syndrome are sleep deprived and miserable.

Jumping Legs

The number of people affected by RLS is somewhat uncertain, but one large study found that almost 8 percent of people in the United States have experienced restless legs sometime in the past year. Three percent are bothered by it two or more times a week. And "bothered" probably isn't the right word — the study categorizes these people as experiencing "moderate or extreme distress."

People with RLS sometimes describe a "tugging" or "creepy crawly" sensation. Until recently, an average physician was unlikely to know what it was.

There are some early references to what appears to be RLS in the scientific literature. An English physician named Thomas Willis wrote a description in 1683:

"Wherefore to some, when being in bed they betake themselves to sleep, presently in the arms and legs. Leaping and contractions of the tendons and so great a restlessness and tossing of the members ensure, that the diseased are no more able to sleep, than if they were in the place of the greatest torture!"

.....Earley has a pet theory that RLS may be the body's way of reacting to reduced iron in the brain and saying, in essence, "Go get some iron!"

"5,000 or 10,000 years ago, the major source of iron was meat," he says. "So the guy out running around... was more likely to find meat and iron than the other guy sitting warmly in his cave keeping comfortable."

Studies indicate the RLS is more common in people from Scandinavia and northern Europe. Earley jokes that this could explain the trips taken by the Vikings.

"What could possibly possess a bunch of guys to get in a boat in the middle of winter and row across the Atlantic," he says, "other than a bad case of restless legs!".....

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