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Periodic Limb Movements

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What is it?

Periodic limb movements are when you have episodes of simple, repetitive muscle movements. You are unable to control them. They usually do not keep you from falling asleep. Instead, they severely disrupt your sleep during the night. This can cause you to be very tired during the day. They do not involve a change in body position, stretching a muscle, or a cramp. Instead, the movements tend to involve the tightening or flexing of a muscle. They occur most often in the lower legs. They can occur at two different times:

1. Periodic limb movements while you sleep (PLMS)

2. Periodic limb movements while you are awake (PLMW)

PLMS are much more common. When they occur often through the night, they can disrupt your sleep many times. Normally, you are unaware of the movements or of waking up. A typical movement is for the big toe to extend. Often the ankle, knee or hip will also bend slightly. Though it is less common, this can also happen in your upper arms. The degree to which these movements occur can change from night to night. They usually happen during non-Rapid Eye Movement (NREM) sleep in the first half of the night. When these movements are very severe, then they may also happen while you are awake (PLMW).

An episode will normally last from a few minutes to an hour. Within that time, movements tend to occur every 20 to 40 seconds. They may affect only one of the legs. More often, they will affect both legs. PLMS are quite common. For most people, the movements do not disturb their sleep in a severe way. This means that it is not a sleep disorder. The sleep of the bed partner tends to be affected more often than that of the patient. The movements reach the level of a disorder, periodic limb movement disorder (PLMD), when they disrupt the patient’s sleep and daily life.

This disorder may be a factor in causing you to have any of the following:

  • Depression
  • Bad memory
  • Short attention span
  • Fatigue

Who gets it?

PLMS occur in both children and adults. The chance of having it increases with age, making it very common in the elderly. It occurs in up to 34% of people over 60 years old. Studies have not yet shown how common it is in other age groups. No difference has been noticed in the rate of males and females who have it. The family pattern has not been studied in detail.

PLMS can be influenced and caused by a number of factors. They are commonly found in people who have one of three other sleep disorders:

  1. Restless legs syndrome (RLS)
  2. REM sleep behavior disorder (RBD)
  3. Narcolepsy

Low brain iron may play a role in making PLMS worse.

High rates of PLMS have been found in some people with:

  • Spinal cord injury
  • Multiple system atrophy (a rare neurological disorder)
  • Sleep related eating disorder (SRED)

The following medications are thought to cause PLMS or make them worse:

  • Some antidepressants
  • Lithium
  • Dopamine-receptor antagonists (e.g., some anti-nausea medications)

Data is not certain about a link between PLMS and the following:

  • Kidney disease
  • Parkinson disease
  • ADHD (attention-deficit/hyperactivity disorder)
  • Pregnancy
  • Posttraumatic stress disorder
  • Multiple sclerosis (MS)

How do I know if I have it?

Normally, you are unaware of the movements. This can make it very hard for you to know if you have periodic limb movements. Someone who sleeps in the same bed with you would be more likely to notice the movements.

1. Has someone else told you that your body makes unusual, repetitive movements while you sleep?

2. Do these tend to occur in your lower legs?

3. Do you feel like you are never well-rested, even after a full night of sleep?

4. Are you often very tired during the day?

If your answer to each of these questions is yes, then you might have PLMD.

It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

  • Another sleep disorder
  • A medical condition
  • Medication use
  • A mental health disorder
  • Substance abuse

Do I need to see a sleep specialist?

For most people, the movements do not disturb their sleep in a severe way. They do not need to seek medical help. In other cases, severe movements can greatly disturb your sleep and life. In this case, you will want to see a sleep specialist. You will need someone with the proper training and experience to help treat it.

What will the doctor need to know?

You should complete a sleep diary for two weeks. This will give the doctor clues as to what might be causing your problems. You can also rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life. The doctor will need to know your complete medical history. Be sure to inform him of any past or present drug and medication use. Also tell him if you or a relative have ever had a sleep disorder.

Will I need to take any tests?

Your doctor will likely have you do an overnight sleep study. This is called a polysomnogram. The polysomnogram charts your brain waves, heart beat, and breathing as you sleep. It also records how your arms and legs move. Not only will it keep track of your movements, it will also help detect any other sleep disorder that you may have.

How is it treated?

When it is necessary to treat PLMS, the same drugs that are used for restless legs syndrome also work for PLMS. These include drugs that replace a chemical in the brain called dopamine. These drugs are also used to treat Parkinson’s disease. However, if you have PLMS, you are not at an increased risk of getting Parkinson’s disease. Other medications used include the following:

  • Sleeping tablets
  • Some anti-seizure medications
  • Narcotic pain killers

    Reviewed by Donald R. Townsend, PhD
    Updated May 16, 2006


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