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Periodic Limb Movement Disorder

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The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

Periodic Limb Movement Disorder (PLMD) is a sleep disorder characterized by the involuntary movement of the limbs while sleeping. It is previously known as nocturnal myoclonus. PLMD is different from Restless Legs Syndrome (RLS). RLS occurs when a person is awake or trying to sleep while PLMD happens when a person is asleep. RLS is also a voluntary movement that happens in order to relieve discomfort in the legs. On the other hand PLMD is involuntary and the person who suffers from it is often unaware of these movements.

What are the symptoms of PLMD?

It is common for a person suffering from PLMD to complain of excessive daytime sleepiness and falling asleep during the day. They also have difficulty falling asleep during the night. Those with PLMD also have difficulty staying asleep throughout the night.

The most common symptom of PLMD is involuntary limb movements while sleeping. These limb movements occur at periodic intervals. The intervals of these movements are anywhere between 20-40 seconds apart. These movements often occur during the first half of the night when a person is still at non-REM sleep stages.

What causes PLMD?

There are two types of Periodic Limb Movement Disorder: Primary LMDB or Secondary LMDB. They are differentiated by their cause.

The cause of Primary PLMD is unknown. Although it is believed to be associated with abnormalities in the regulation of nerves traveling from the brain to the limbs, we are still not sure what causes these abnormalities. According to the National Sleep Foundation Primary PLMD is quite uncommon. It is also not considered severe but complications that might arise from Primary PLMD may be a cause for concern.

On the other hand Secondary PLMD is the result of another medical problem. There are many causes of Secondary PLMD. Most of these can also cause Restless Legs Syndrome. Other causes include:

  • Diabetes mellitus
  • Spinal Cord Tumor
  • Spinal Cord Injury
  • Iron Deficiency

Aside from the above, the following medical conditions may also trigger Secondary PLMD:

  • Sleep Apnea – a sleep disorder wherein a person has shallow breathing or pauses in breathing during sleep.
  • Uremia – a condition where poor kidney function results in the build-up of waste products in the blood.
  • Narcolepsy – A sleep disorder that causes a person to experience excessive sleepiness. A person afflicted with narcolepsy experiences an overpowering urge to sleep during waking hours. It can cause a person to fall asleep even while performing activities whenever and wherever they are.
  • Multiple System Atrophy – a rare neurological disorder
  • Anemia – a medical condition caused by the low level of hemoglobin. Hemoglobin is the substance that carries oxygen in the blood.
  • REM behavior disorder – a type of sleep disorder where a person has vivid dreams that they act out. This results in the interruption of their sleep.
  • Medications – several medications can cause a person to experience symptoms of PLMD. This includes some types of antidepressants, antipsychotics, and antinausea medications

Can PLMD be treated?

No, there is no known treatment for PLMD. However, there are ways to relieve their symptoms. Because of PLMD’s similarity to RLS most of the medications used to treat PLMD and RLS are the same.


Benzodiazepines are medications that control muscle contractions. They are also classified as sedatives so they can help patients sleep through the movements caused by PLMD. The drug Clonazepam has been proven effective in reducing the total number of movements caused by PLMD.

Dopaminergic Agents

These are drugs that increase the levels of dopamine in the brain. Dopamine is a neurotransmitter responsible for regulating muscle movements.

GABA agonists

GABA agonists inhibit the release of neurotransmitters that stimulate muscle contractions.


These medications can help reduce muscle contractions. Gabapentin is the most widely prescribed anticonvulsant for the treatment of PLMD.

Additional Resources:

The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. Read our full medical disclaimer.

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