Periodic Limb Movement Disorder

What Is PLMD?

PLMD stands for periodic limb movement disorder, a sleep disorder in which a person’s arms or legs twitch and jerk repeatedly during sleep Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source . These movements are called periodic limb movements of sleep (PLMS). Between 4% and 11% of adults have PLMD, and the movements aren’t usually painful or uncomfortable. While they can include arm and hand movements, they most often involve:

• Flexing the foot and big toe backward
• Bending legs at the knees
• Bending legs at the hips
• Kicking

These movements happen in bursts that last between .5 and 10 seconds. Between bursts of movement, a sleeper often lies still for up to 90 seconds. These movements disrupt sleep for people with PLMD, even though they might not realize they are waking up throughout the night. These brief wake-ups can cause daytime tiredness and potential problems at home, school, or work.

PLMD is not the only disorder associated with periodic limb movements of sleep. These movements can also occur in people with restless legs syndrome, obstructive sleep apnea, narcolepsy, and neurological disorders such as Parkinson disease. Treatment of the contributing disorder may help to resolve the secondary movements.

What Causes PLMD?

Scientists are still trying to find the causes of periodic limb movement disorder (PLMD). Some research shows that low iron levels are linked to periodic limb movements, so iron deficiency may contribute to PLMD Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .

Another theory suggests that periodic limb movements happen during sleep when nerves in the spinal cord make mistakes while sending signals Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source . Relatedly, other experts have proposed that in people with PLMD, the nerve pathways involved in limb movements become hyperexcitable during certain points of the sleep cycle, potentially because of low levels of dopamine, a neurotransmitter and hormone involved in pleasure, movement, and motivation.

Although there is still uncertainty about the causes of PLMD, research has clearly shown that some people have a higher risk of developing periodic limb movements of sleep than others. These include:

• Older adults
• Men and people assigned male at birth
• Individuals with obesity
• People with diabetes
• Smokers
• People with low iron levels
• People with low magnesium levels
• Individuals with inactive lifestyles
• People who take antidepressants

What Are the Symptoms of PLMD?

Repetitive leg and arm movements during sleep are the primary symptoms of periodic limb movement disorder (PLMD), but many people with the disorder aren’t aware of these movements. While periodic limb movements can disturb sleep, people who experience them usually don’t wake up for long enough to recall them. Other PLMD signs and symptoms include:

• Excessive daytime sleepiness: The sleep disturbances caused by PLMD lead to fragmented, low quality sleep and, ultimately, excessive sleepiness during the day.
• Decreased ability to function: Sleepiness and sleep deprivation caused by PLMD may interfere with a person’s ability to maintain relationships, fulfill work responsibilities, or do school work Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source .
• Mood alterations: PLMD may lead to moodiness or distress.
• Accounts from bed partners: Bed partners may describe having their sleep interrupted by movements that shake the bed or complain about being kicked.
• Sleep difficulties: For some people, PLMD can trigger insomnia symptoms, making it difficult to fall asleep or stay asleep at night.

How Is PLMD Diagnosed?

Doctors diagnose periodic limb movement disorder (PLMD) by confirming a high number of periodic limb movements during sleep and ruling out other conditions that could be causing those movements. If you suspect you have PLMD, your doctor will likely begin by asking questions about daytime tiredness, reports from your sleeping partner, and other possible indicators of PLMD.

 Your doctor might ask:

• If any pain or discomfort accompanies the limb movements
• Whether you are aware of movements when they take place
• If your entire body moves during episodes, or just your limbs

Questions like these can help your doctor differentiate PLMD from other conditions.

If your doctor thinks you might have PLMD, you may be asked to undergo an overnight sleep study in a specialized facility. During a sleep study, medical professionals record muscle activity to identify periodic limb movements. Adults must experience more than 15 distinct bursts or series of movements per hour and children must have more than five per hour for an official diagnosis of PLMD.

You may be asked to undergo additional testing, such blood tests such as a ferritin check to measure your iron levels, to help determine treatment decisions. If the ferritin level is <70 mcg/L blood, this may be deemed abnormal (even if it is technically within the normal laboratory range for adults).

What Are the Treatments for PLMD?

Research on possible treatments for periodic limb movement disorder (PLMD) is limited, and some experts question whether or not the disorder should be treated at all Trusted Source UpToDate More than 2 million healthcare providers around the world choose UpToDate to help make appropriate care decisions and drive better health outcomes. UpToDate delivers evidence-based clinical decision support that is clear, actionable, and rich with real-world insights. View Source . If medical tests have revealed an iron deficiency, your doctor may recommend taking iron supplements or an intravenous iron infusion. Melatonin supplements, which are the body’s natural sleep hormone, may reduce limb movements in some people with PLMD.

Limited evidence suggests that certain prescription drugs may improve symptoms for some people with PLMD. These include medications such as ropinirole or pramipexole that activate dopamine receptors in the brain and that stabilize the electrical activity of certain nerves. Some prescription sedatives, such as clonazepam, have been shown to improve sleep in people with PLMD, but these may not be commonly recommended, as they don’t actually reduce movements caused by the disorder.

If you’ve been diagnosed with periodic limb movement disorder, talk to your doctor about what treatment options might be right for you.

“It is important to recognize that PLMS are measured by an in-center sleep study, PLMD occurs when consequences like sleepiness or disruption of the bed partner occurs, and restless legs syndrome (RLS) differs and is a clinical diagnosis that is based on symptoms and does not require a sleep study to identify.”

Dr. Brandon Peters

Sleep Physician, Sleep Psychiatry Expert