When you have restless legs syndrome (RLS), one of the questions at the front of your mind is likely: Why? Unfortunately, in most cases doctors don’t know what’s behind the disorder. Here’s what they do know: In some people, RLS may be due to insufficient levels of iron in the brain or a problem with the brain’s ability to use iron. Normally, the brain uses iron to make the neurotransmitter dopamine. This chemical works in parts of your brain that control your body’s movements. Problems with dopamine can lead to involuntary movements such as those experienced by people with RLS. Research has found several other factors that can lead to RLS. These include: Genetics. Having family members with the disorder increases your risk for RLS. Gender. Women are two times more likely to develop RLS than men. Pregnancy accounts for the difference. Population studies that exclude pregnant women, shows an men and women have an equal likelihood of developing RLS. Age. While RLS can occur at any age—even children can have RLS—those with more severe cases tend to be middle-aged and older. Chronic diseases. Certain health problems may affect the levels of iron in your brain or affect the part of the brain that controls body movements and cause RLS. Some examples are: Parkinson’s disease Rheumatoid arthritis Kidney failure Diabetes Pregnancy. Many women experience RLS symptoms during their final trimester. Fortunately, symptoms usually go away within four weeks of giving birth. Medications. Certain medications used to treat other health issues may lead to RLS. Symptoms usually resolve once you stop taking the medicine. Common culprits include: Antinausea medicines Antidepressants Antipsychotics Cold and allergy medicines with antihistamines Alcohol, caffeine, and tobacco. Symptoms may improve if you reduce or stop using these substances.