Types and Causes of Restless Legs Syndrome

Restless legs syndrome (RLS) is a sleep disorder that causes unpleasant sensations in the legs. People describe these sensations as aching, throbbing, itching, pulling, or tingling. Twitching, jerking, and the irresistible urge to move the legs also happens.^1,2

Restless legs syndrome is more common in Caucasians in North America and Europe and less common in people from Asia.^2,3

What causes restless legs syndrome?

Doctors do not fully understand what causes RLS. In people with a family history of RLS, parts of chromosomes 2q, 2p, 6p, 9p, 12q, 14q, 15q, and 20p seem to be altered. Other studies point to the MEIS1 gene.

These genetic changes seem to cause problems in the part of the brain that controls movement, the basal ganglia. This area of the brain uses dopamine to create smooth, purposeful muscle movement. The brain in people with RLS also seems to have problems processing iron correctly.^1,2

Types of restless legs syndrome

There are 2 types of restless legs syndrome, primary and secondary.

Primary PRLS

Primary RLS is also called idiopathic, which means the cause is unknown. Within primary RLS there are 2 subgroups. People who develop restless legs before age 45 generally have inherited the condition from someone in their family. People who develop restless legs after age 45 usually do not. Symptoms may come and go but tend to get worse the older the person gets.²

Secondary RLS

Secondary RLS is caused by another health condition. With secondary RLS, symptoms tend to get better once the underlying condition is treated. People who are at higher risk of developing RLS include those with:^1-5

• Anemia caused by low iron levels
• End-stage kidney disease
• Diabetes
• Multiple sclerosis
• Rheumatoid arthritis
• Parkinson’s disease
• Peripheral neuropathy
• Heart disease
• COPD
• Spinal cord injuries

About 1 in 4 pregnant women develop RLS, most often in the third trimester. It often disappears in the weeks after birth.²

More than 80 percent of those with RLS also have periodic limb movement disorder (PLMD). RLS is felt when the person is awake. PLMD occurs during sleep. In PLMD, the legs, and sometimes arms, twitch or jerk every 20 to 40 seconds. Sometimes this goes on all night.^6-8

Triggers for restless legs syndrome

Sitting still or trying to sleep is the most common trigger of RLS. The unpleasant creeping, tingling feelings are most often felt deep in the lower legs, between the knees and ankles. Usually, the feelings happen in both legs.²

Some people feel these symptoms during the day when sitting still for long periods. This can make it hard to sit through long meetings, movies, or plane rides. The uncomfortable sensations often get better when the person gets up and moves the legs.^1,4

Other triggers of RLS can vary greatly by individual and include:^1-4,6

• Certain drugs
• Caffeine
• Alcohol
• Smoking
• Lack of sleep or being overly tired
• Low folic acid levels (vitamin B9)

The drugs most often tied to RLS symptoms are antihistamines, anti-nausea medicines, and some antidepressants.¹

Gender and restless legs syndrome

Many studies report that women are twice as likely to have RLS than men. However, a few studies have found that women only have a slightly higher risk of developing RLS. This does not include the women who develop RLS during pregnancy.³

Age and restless legs syndrome

Rates of RLS increase with age in North American and European countries but not in Asian countries.³