What Causes Restless Leg Syndrome?

Although its name may sound lighthearted, restless leg syndrome (RLS) can be a troubling disorder. Symptoms include itching, burning, or aching in the legs, particularly when you’re at rest, and an overwhelming desire to move your legs. RLS can lead to severe sleep disturbances.

According to the National Heart, Lung, and Blood Institute, about five to 15 percent of Americans with RLS have a family member who also has it. There is no specific test for RLS. Diagnosis is based on symptoms, a physical exam, and elimination of other potential conditions.

So, who gets RLS and why?

RLS is not just an adult condition—children get it, too. The Restless Leg Foundation (RLF) reports that approximately 1.5 million children and teens in the U.S. have RLS. When symptoms appear in childhood, there is often a familial link. A parent has a 50/50 chance of passing the RLS trait on to their children, according to RLF.

Symptoms in children are the same as in adults. These symptoms may lead to sleeping difficulties that can easily be misinterpreted as a behavioral problem. 

The Journal of Midwifery and Women's Health says that about 26 percent of pregnant women in the U.S. have RLS. Symptoms usually start in the third trimester. The reasons pregnant women are particularly susceptible to RLS aren’t clear, but it may be related to hormonal fluctuations, mineral deficiencies, or an imbalance in a neurotransmitter called dopamine. The good news is that in most pregnancy-related cases of RLS, symptoms disappear within days or a few weeks after the baby is born.

According to the National Heart, Lung, and Blood Institute, research indicates that lack of iron or faulty use of iron may trigger RLS. Our brains require iron to help produce dopamine, a chemical that helps the brain control movements. Some conditions can affect how our bodies use iron. Among them are Parkinson’s disease, diabetes, rheumatoid arthritis, and kidney failure. Pregnancy may also cause iron deficiency (anemia).

Some medications can trigger RLS, including medications to prevent nausea and dizziness. Cold and allergy medications containing antihistamines and calcium channel blockers may also cause RLS. So can antidepressants and antipsychotics. In most cases, symptoms go away when you stop taking the medication. If you’re taking prescription medication, don’t stop taking it until you speak to your doctor.

Other substances, like tobacco and alcohol, can cause RLS or intensify symptoms. Try to avoid them to better manage the condition.

Sometimes, RLS is more than RLS. It can be a symptom of another medical condition. In these cases, it is called secondary RLS. For example, nerve damage to the legs can cause RLS. Nerve damage can be the result of an injury, and it can also be a side effect of diabetes. Other diseases associated with RLS include end-stage renal disease, rheumatoid arthritis, Parkinson’s disease, and attention-deficit hyperactivity disorder (ADHD).

Anyone can develop RLS, but it is diagnosed more frequently in women than in men. Although people with a family history of RLS tend to get it early on, in general, risk increases with age. Most people are diagnosed in midlife. People with Northern European ancestors are more likely to have RLS than people of any other race or ethnicity.

If you have symptoms of RLS that won’t go away, make an appointment to see your doctor. Be prepared to give a complete medical history. Your doctor will want to check for underlying conditions. List all your over-the-counter and prescription medications and supplements.

Unless the cause is pregnancy, medication, or a diagnosed medical condition, doctors can’t always pinpoint the RLS trigger. Still, there are some medications and other remedies that may be able to help ease your symptoms so you can get a good night’s sleep.