In 1672, an English physician, Sir Thomas Willis, described people who can't fall asleep because of "leapings and contractions" of the arms and legs. Sir Willis wrote that "restlessness and tossing" could be so severe that these people "are no more able to sleep, than if they were in a place of the greatest torture."
Sir Willis was the first to describe what is now called restless leg syndrome (RLS). Today, experts estimate that as many as 8 percent of people in the United States have this neurological condition. And while the cause of RLS syndrome is unknown, a family history of the condition is seen in approximately 50 percent of patients, suggesting a genetic form of the disorder. Individuals with inherited RLS tend to be younger when symptoms start and have a slower progression of the condition.
Sometimes it's hard for people to describe exactly what they are experiencing. They say they feel a burning sensation. They use words like "creeping" and "tugging." Or they say they feel like insects are crawling inside their legs. What these people share in common are unpleasant feelings that can only be relieved by voluntary movement. They need to keep their legs in motion. They cross and uncross their legs. They pace. In bed, they toss and turn.
People with RLS usually find their symptoms most noticeable in the evening, especially when they first try to go to sleep. But the unpleasant sensations can also arise during long car trips or airplane flights or other long periods of inactivity, such as during meetings or while watching a movie.
