It’s a creepy-crawling-itching-burning feeling that strikes just as you are ready to relax into bed. The urge to move your legs can make sleep elusive. To get relief from restless legs syndrome (RLS) you need to walk around. And if you’re walking the house long after the sun has set, odds are you are not well rested.

RLS is considered a sleep disorder because it interrupts sleep, but also because it occurs at the same time each day, says Lisa Shives, M.D., spokesperson for the American Academy of Sleep Medicine and medical director of Northshore Sleep Medicine in Evanston, IL. “By definition, restless legs syndrome happens in the evening and has a circadian rhythm,” she says. “It tends to occur at about the same time on the 24-hour clock, in the evening or when a person gets into bed.” .

A Family Link
Cases that occur before age 35 usually have a family history of the disorder. The severity of RLS increases as you age, though when symptoms occur later in life, they often come on suddenly and may not get worse with age, according to the National Heart, Lung and Blood Institute. Of the 12 million Americans who suffer from RLS, women and people of Northern European descent are at greatest risk. .

The Iron Link
The cause of RLS is unknown, although researchers do believe it is connected to the way the body uses iron. Iron helps make dopamine, a chemical that works in the part of the brain responsible for movement. Researchers are unsure whether RLS sufferers don’t have enough iron or if their brains aren’t adequately using it. .

“We think the common denominator is that it lowers people’s iron,” Dr. Shives says. “For example, 30 percent of pregnant women get RLS. Anemia and low iron are common in pregnancy.” .

Fibromyalgia, kidney failure, Parkinson’s disease, diabetes, rheumatoid arthritis and iron deficiency can all trigger RLS, as can medications to treat nausea, depression, allergies and high blood pressure. Even though stopping these drugs may end the symptoms, you should consult your doctor before you stop taking any medication. .

Treatable But Not Curable
Some medications used to treat Parkinson’s disease are also approved to treat RLS, but people with RLS are not at increased risk of Parkinson’s. Some people with RLS find relief from home remedies, such as warm baths and hot or cold compresses. If your legs are keeping you up at night, talk to your doctor or a sleep specialist. .