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What Is RLS?

Crawling Sensation in Legs During Rest May Represent Restless Legs Syndrome


Updated February 19, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Restless legs syndrome (RLS) is one of those conditions that sounds a little too strange to be true, but if you have ever laid down to fall asleep and felt an uncomfortable sensation of bugs crawling under your skin, you may be all too familiar with what RLS is. This condition may leave you kicking your legs as you fall asleep, but a better understanding of the disorder and its causes may lead to the treatment and rest that you need.

What Is RLS?

RLS is a movement disorder that is characterized by unpleasant feelings in the legs associated with a need to move. The sensations (called paresthesias) may include aches, pulling, itching, or even the feeling of bugs crawling under the skin. The symptoms typically come on during periods of rest, especially at night, and are relieved by movement. They may make it hard to fall or stay asleep, resulting in insomnia.

There are four features that are used to diagnose RLS and these include:

  1. An urge to move the legs, usually accompanied or caused by uncomfortable and unpleasant sensations in the legs.
  2. The urge to move or unpleasant sensations begin or worsen during periods of rest or inactivity such as lying or sitting.
  3. Sensations that are relieved by movement, such as walking or stretching, as long as the activity continues.
  4. Sensations that are worse during the evening or night.

Symptoms typically come on within 15 to 30 minutes of resting. In very severe cases, the problems may occur with any seated activity during the day, such as sitting in meetings or in a movie theater. This may lead to fidgeting, constant movement, or the need to kick or massage the legs to relieve the symptoms. Some people are so bothered by the symptoms at night that they will get out of bed. Individuals with RLS may experience periodic limb movements of sleep (PLMS), which consist of sudden jerking leg movements involuntarily during sleep.

How Common Is RLS?

Mild symptoms associated with RLS occur in 5 to 15 percent of the population. It seems to increase as we get older and occurs more commonly in women.

There are two types of RLS. The first, called primary (or idiopathic) RLS, has no clear cause and tends to run in families. The other type, called secondary RLS, occurs as the result of separate conditions, including iron deficiency, diabetes, pregnancy, and more.

Diagnosis and Treatment of RLS

RLS is diagnosed using the four criteria described above. A sleep study called a polysomnogram is not necessary but it may be helpful if the condition is resistant to treatment. It is important to identify any contributing causes so that these can be addressed appropriately. The treatment of RLS may include a combination of medications, exercises, and other therapies.


Allen, RP et al. "Restless legs syndrome prevalence and impact: REST general population study." Arch Intern Med. 2003;163:2323.

American Academy of Sleep Medicine. "International classification of sleep disorders: Diagnostic and coding manual." 2nd ed. 2005.

Hogl, B et al. "Restless legs syndrome: a community-based study of prevalence, severity, and risk factors." Neurology. 2005;64:1920.

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