Periodic Limb Movement Disorder

Written by Alesandra Woolley, Content Writer

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In this Article

Periodic limb movement disorder (PLMD), also known as nocturnal myoclonus, is a condition where limbs move involuntarily during sleep, thus disrupting normal sleep patterns.

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Do you experience restless sleep at night? While it could just be a side effect of pent-up energy, your restless nighttime movements could have a more serious cause.

Periodic Limb Movement Disorder (PLMD) is a sleep disorder that causes people to involuntarily move their legs and arms throughout the night. According to research experts, people with PLMD are at an increased risk of other health complications¹ such as high blood pressure, stroke, and heart disease.

Keep reading to learn all about PLMD, including what causes it, how you can identify it, and what you can do to treat this sleep disorder.

What Is Periodic Limb Movement Disorder?  

Periodic limb movement disorder (PLMD), also known as sleep myoclonus or nocturnal myoclonus, is a sleep disorder in which someone moves their limbs involuntarily while sleeping, disrupting their normal sleeping patterns.¹ 

According to the American Academy of Sleep Medicine (AASM), these movements usually involve flexing or tightening muscles². They add that the movements usually occur in the lower legs but can also happen in the upper arms. These periodic leg movements usually occur at intervals 20 to 40 seconds apart and are more likely to happen during non-REM sleep in the first half of the night.²

Not only can these involuntary movements disrupt the sleep of the person with PLMD, but they also — perhaps to an even greater extent — can interfere with the sleep of their bed partner.  

What Causes Periodic Limb Movement Disorder?

The exact cause of PLMD is not known, but it may be related to a variety of medical conditions or substances, such as:  

• Restless leg syndrome¹
• Parkinson’s disease²
• Kidney disease/uremia² 
• Other sleep disorders, such as narcolepsy, REM behavioral disorder, sleep-related eating disorder, and obstructive sleep apnea^{1, 2}
• Neurodevelopmental and genetic disorders, such as ADHD²
• Spinal cord injury²
• Iron deficiency¹ 
• Caffeine¹
• Medications such as antidepressants, dopamine-receptor antagonists (anti-nausea drugs), lithium, and antihistamines for allergies² 
• Pregnancy²
• Post-traumatic stress disorder (PTSD)²
• Multiple sclerosis²
• Multiple system atrophy²

PLMD affects an estimated 4 percent of adults but is more common in the elderly, especially women, with up to 11 percent experiencing symptoms of the disorder, according to a study published in the Journal of Psychosomatic Research³.  

PLMD movements occur when one or more muscle groups suddenly contract. The root cause of those contractions, however, is largely unknown. One theory is that issues related to the brain chemical dopamine may contribute⁴ to these muscle contractions.

Periodic Limb Movement Disorder vs. Restless Leg Syndrome

While there appears to be a connection between PLMD and RLS, with as many as 80 percent of people with RLS experiencing symptoms of PLMD the two sleep disorders are different.¹

PLMD movements generally occur during sleep and are completely involuntary, with the individual being unaware of the movement, though they likely will experience sleep disturbances.²

RLS symptoms, on the other hand, are experienced when the individual is awake and aware, often intensifying at night⁵ when the person is trying to fall asleep. Symptoms of RLS include an unpleasant sensation that causes an irresistible urge to move the legs. The sensations are usually described as an itching, crawling, pulling, aching, throbbing, or pins and needles sensation.⁵ 

Common Periodic Limb Movement Disorder Symptoms

The most common symptoms first identified by people with PLMD are typically not leg movements at all, as they tend to occur when the person is asleep and unaware. The first signs are usually poor sleep and daytime sleepiness.² In fact, people with PLMD may not even know about their leg movements unless their bed partner tells them or the symptom is identified during a sleep study. 

Overall, symptoms include:  

• Repetitive, periodic limb movements in sleep 
• Sleep disruption or restless sleep
• Excessive daytime sleepiness
• Irritability 
• Poor school or work performance

What Are the Leg Movements Associated with PLMD like? 

According to the AASM, the movements are varied, involve either one or both legs, and can be seen in any of the following ways²: 

• Knee, ankle, and big toe joints all flexing or bending at the same time
• Rhythmic and repetitive, occurring every 20-40 seconds

The Effects of Periodic Limb Movement Disorder

PLMD is not considered medically serious, but it is cause for concern. If left untreated, this disorder can cause sleep problems that can lead to impact your daily life and overall health. Not only can you experience bouts of exhaustion and daytime fatigue, but as mentioned, people with PLMD are more likely to develop hypertension, a stroke, or a heart attack.¹

PLMD may also be an indicator of a serious underlying medical condition such as kidney disease⁶.

How Is Periodic Limb Movement Disorder Diagnosed?

As mentioned, you may not know you have PLMD unless your bed partner tells you or your symptoms of excessive daytime sleepiness, insomnia, or fatigue are extreme enough to send you to your doctor or a sleep specialist. 

If your doctor suspects, you have PLMD, they’ll likely recommend you take a polysomnography (sleep study) at a sleep center. During the study, the specialist will monitor your arm and leg movements, as well as your brain, heart rate, and breathing activity.¹ 

Body movements that occur during sleep are also seen in other sleep behavior disorders. As a result, diagnoses such as RLS, sleep-related breathing disorder, narcolepsy, and sleep-related eating disorder, must first be ruled out before a diagnosis of PLMD is given.  

How to Treat Periodic Limb Movement Disorder

Treatment for PLMD may include medications also used in the treatment of restless legs syndrome and Parkinson’s disease. According to the AASM, these medications help replace dopamine levels in the brain. Your healthcare provider may also suggest iron supplements if your iron levels are low since iron deficiency is a potential risk factor for PLMD.² 

You may also want to reduce your intake of caffeine, especially at night before bedtime, as they may contribute to your PLMD symptoms. 

Frequently Asked Questions

Is Periodic Limb Movement Disorder dangerous?

PLMD itself isn’t considered dangerous, though you could run of risk of accidentally kicking or hitting your partner when you move. However, this disorder can pose a risk to your long-term health since research shows you’re more likely to develop stroke, heart disease, and hypertension.¹

Daytime sleepiness is also a symptom of PLMD.² This can be dangerous because if you’re overly tired during the day, you’re more at risk of getting into an accident.

How do I know if I have Periodic Limb Movement Disorder?

You probably don’t know you have PLMD unless your bed partner tells you that you kick a lot at night because the leg movements occur while you’re sleeping and unaware. People generally go to their doctors complaining of fatigue or other conditions. You cannot be diagnosed, however, without a formal sleep study, which records your leg movements and rules out other conditions.

Is Periodic Limb Movement Disorder different from Restless Leg Syndrome?

Yes. Periodic Limb Movement Disorder occurs when you are asleep and unaware your legs are moving.² Restless Leg Syndrome is an unpleasant sensation in the legs that makes you want to move them.³ RLS, however, is a risk factor for PLMD.¹

Does Periodic Limb Movement Disorder lead to Parkinson’s?

There is no evidence that PLMD is a risk factor for Parkinson’s disease. However, people with Parkinson’s are at greater risk of developing PLMD.²

Conclusion

Periodic limb movement disorder is a sleep-disrupting condition that affects about 4 to 11 percent of adults, many of whom are unaware they thrash about at night unless they are told by their bed partner.¹ Instead, they wake in the morning feeling groggy and suffer from excessive sleepiness during the day. If you notice signs of PLMD, talk with your doctor or go directly to a sleep specialist. Treating your condition can help ensure you get a good night’s sleep and are well-rested to tackle your day ahead.

Alesandra Woolley

Editor

About Author

Growing up in the City That Never Sleeps, she learned the hard way how important a good night of rest really is. She’s made it her mission to help others realize the same. On any given day, you’ll find Alesandra in our Mattress Lab testing the latest mattress models, interviewing specialists on the importance of sleep, or curating the most helpful content for our readers. Alesandra’s been featured in Business Insider, USA Today, MarketWatch, Elite Daily and the NY Post for her perspectives on sleep health.

Stomach Sleeper

Education & Credentials

• Certified Sleep Science Coach