New research suggests that 23% of people have restless leg syndrome, or RLS, which is much higher than previously reported rates of 3% to 10%.
Restless leg syndrome causes unpleasant sensations in the legs when a person is at rest, triggering an uncontrollable urge to move the legs to get relief.
The cause is unknown, but researchers suspect that an imbalance in the movement-regulating brain chemical dopamine plays a role. Drugs that increase dopamine activity are sometimes used to treat RLS.
Read: Rest those restless legs
The new research, which was presented this week at a medical conference in San Diego, California, suggests that, overall, non-African-Americans experience RLS four times more often than African-Americans.
Furthermore, two out of five Caucasian women were found to have RLS, nearly four times the incidence of RLS in African-American women and the highest incidence among all groups.
"Some risk factors for restless legs syndrome appear to be more common among women," co-researcher Dr Ammar Alkhazna, from the University of Missouri, Kansas City, said.
"Women are more likely to be iron deficient than men and have rheumatoid arthritis, which are known risk factors for RLS."
How the study was done
The findings stem from a study of 190 patients who were selected during visits to a primary care clinic and were evaluated for RLS.
Read: Restless legs linked to heart risk
One hundred three of the participants were African American and 87 were non-African-American, with Caucasians the majority. In both ethnic groups, roughly 60% were female. The average ages of the African American and non-African-American groups were 53 and 50 years, respectively.
In non-African Americans, the RLS diagnosis was definite in 36% and negative in 64%. In African Americans, the diagnosis was definite in 12%, probable in 4%, negative in 83%, and uncertain in 1%.
"This is the first study to show such a striking difference in RLS prevalence across racial groups," Alkhazna said. "This likely reflects a combination of factors, including a genetic predisposition to RLS, diet including iron intake medications, and possibly culture.
Could dark chocolate help ease poor leg circulation
Office strolls restore blood flow to the legs
NWU student on two-year waiting list for prosthetic leg