Periodic Limb Movement Disorder: Symptoms, Diagnosis, and Treatment

If your partner complains that your legs twitch and jerk while you are sleeping, you may have periodic limb movement disorder. Unlike other sleep disorders, PLMD occurs while you’re sleeping and therefore does not interfere with your ability to fall asleep or stay asleep.

Periodic limb movement disorder does not involve changes in your body position or noise. Still, the tightening and flexing of the muscles in your lower extremities are palpable movements to your partner. You may not feel anything, but periodic limb movement disorder can be quite a nuisance to your bedmate, causing you both to be tired and irritable during the day.

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“Periodic limb movements in sleep are repetitive bursts of muscle activity, usually in the lower limbs, which are sometimes accompanied by an arousal,” says Dr. Nayantara Santhi.

“Recent evidence suggests that PLMs may be highly prevalent in the general population and its occurrence increases with age. An interesting finding is that PLMs exhibit a circadian cycle and are maximal during the early part of the night or early sleep period.”

This article is a deep dive into periodic limb movement disorder. It examines what PLMD is, common symptoms, how it’s diagnosed, and possible treatments.

What is Periodic Limb Movement Disorder?

Periodic limb movement disorder is a rare sleep disorder, and it’s the only movement disorder that occurs while the patient is fully asleep. Repetitive limb movements are hallmarks of the condition. Typically these movements tend to play out in the lower extremities and feet. However, in some patients, movement can occur in the upper extremities as well.

While most people naturally move in their sleep, the movements associated with periodic limb movement disorder typically present as spontaneous limb movements, muscle twitches, and jerking. Flexion of the ankle, knees, and hips and an extension of the big toe are also hallmarks of the condition. It’s worth noting that no two nights are the same for those who suffer from PLMD. There can be a significant difference in limb movements from one night to the next and differences in the frequency of movements.

Researchers have found Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source that each episode of PLMD can last anywhere from 0.5 to 10 seconds, and they occur regularly at  5 – 90 second intervals. Episodes of periodic limb movement disorder typically occur during the non-rem sleep stages or stages 1 and 2.

Sex does not appear to be a factor in developing periodic limb movement disorder. It tends to affect men and women equally.

Periodic limb movement disorder was formerly known as nocturnal (night) myoclonus (rapid, rhythmic movements) or sleep myoclonus. However, as research on the condition has evolved, experts have come to discover that PLMD movements are neither rhythmic nor do they occur during sleep. Hence, the terms nocturnal myoclonus and sleep myoclonus are no longer used in reference to periodic limb movement disorder.

Difference Between Periodic Limb Movement Disorder and Restless Leg Syndrome

PLMD can occur alongside Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source other sleep disorders. More often than not, it runs concurrently with restless leg syndrome. Research has even shown that about 80 to 90% of people who have restless leg syndrome also have PLMD.

Now while restless leg syndrome and PLMD may sound similar, run concurrently, and even affect the same parts of the body, the two are distinct sleep disorders.

Restless leg syndrome is a sleep disorder where the individual feels an overwhelmingly uncomfortable or tingling sensation in their legs. In order to relieve that discomfort, the patient knowingly and purposefully moves their legs about. More often than people who suffer from restless leg syndrome find it difficult to fall asleep and stay asleep.

Periodic limb movement disorder, however, is where the individual moves their limbs about while they are sleeping, and they are typically unaware that they’re doing so.

Interestingly, people with Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source restless leg syndrome can have PLMD, but people with PLMD may not have restless leg syndrome.

What Are the Symptoms of Periodic Limb Movement Disorder?

In addition to the toe, ankle, or knee flexion and twitching or jerking of the lower extremities mentioned earlier, the symptoms of PLMD are very similar to those of most sleep disorders and PLMD often includes:

• Disrupted sleep
• Poor sleep quality
• Daytime fatigue or tiredness
• Frequent waking
• Irritability

However, it’s not guaranteed that a person who has sleep issues will have PLMD, or that a person with PLMD will experience poor sleep. PLMD can be associated with poor sleep and not associated with it.

What Causes PLMD?

Periodic limb movement disorders are often classified as primary PLMD or secondary PLMD.

Primary Periodic Limb Movement Disorder

While the exact cause of primary PLMD is still unknown, researchers theorize that the condition may originate in the central nervous system. This type of PLMD is uncommon.

Secondary Periodic Limb Movement Disorder

Although there is no concrete proof, the following risk factors may contribute to secondary PLMD:

• Caffeine consumption
• Iron deficiency/anemia Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source
• Neurodevelopment disorders Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source like ADHD or William’s Syndrome
• diabetes Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source or kidney disease Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source
• Genetics

Some sleep-related disorders may also contribute:

• Restless leg syndrome: As we discussed above, restless leg syndrome is a neurological disorder characterized by an irresistible urge to move the legs, often accompanied by uncomfortable sensations and an inability to find relief while at rest.
• Narcolepsy: Narcolepsy is a sleep disorder marked by excessive sleepiness and an overwhelming urge to sleep during your waking hours.
• Obstructive sleep apnea: Obtructive sleep apnea or OSA is a sleep disorder that causes you to stop breathing multiple times per night.
• REM Sleep Behavior Disorder: REM Sleep Behavior Disorder (RBD) is a sleep disorder where individuals physically act out their dreams, often with vivid and sometimes violent movements, during the REM (rapid eye movement) stage of sleep.

To be clear, there is no definitive proof for any of the above, so, at this point, it is all conjecture.

Who is Most at Risk for PLMD?

In addition to running concurrently with restless leg syndrome, PLMD is also quite common Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source in patients with narcolepsy or REM Sleep Behavior Disorder.

Age also appears to be a risk factor for periodic limb movement disorder. While periodic limb movement disorder can begin at any age, more often than not, it seems to make its first appearance around age 40. It also appears that the prevalence of PLMD tends to increase with age. Studies have shown an estimated 5 to 6 % prevalence in the 30 to 49 age group, and that number jumps up to 30% in people who are 50 or older.

How is Periodic Limb Movement Disorder Diagnosed?

Periodic limb movement disorder is quite rare, so if your primary care physician is unfamiliar with the condition or doesn’t feel comfortable making a diagnosis, they may refer you to a specialist or a sleep clinic.

Typically, sleep specialists will suggest you start off with a sleep diary to be completed over a two-week period. Sleep diaries are essentially notes and details on your sleep habits, including:

• What time you go to sleep
• What time you wake up
• How long it takes you to fall asleep
• Any notable interruptions
• Perceived sleep quality
• How you feel throughout your day

Sleep diaries Verified Source National Library of Medicine (NIH) World’s largest medical library, making biomedical data and information more accessible. View source are a powerful tool. They can help your sleep specialist get to the root of the problem.

When completing a sleep diary, keep in mind that no detail is too small. Things that may seem insignificant to you may prove quite helpful to your doctor. In addition to a sleep diary, your doctor may have you do a polysomnogram or a sleep study.

Sleep studies typically record your brain waves, sleeping heart rate, breathing, as well as any and all disturbances. In this case, sleep specialists or sleep techs will also monitor how your arms and legs move. Polysomnograms are incredibly helpful when it comes to nailing down whether or not you have a sleep disorder such as PLMD.

Treatments and Management Options for PLMD

If your doctor determines that your PLMD is not severe and it does not significantly disturb your sleep, your quality of life (or your partner’s), then you may not need to do anything at all.

If your PLMD does disrupt your life and it rocks the boat in your relationship, you may want to steer clear of caffeine, particularly before bed. Caffeine has been shown to exacerbate the symptoms of periodic limb movement disorder, so those who suffer from it should take care to avoid it. Remember that caffeine is also found in sodas, tea, and even chocolate, in addition to coffee.

Remember, too, that there are plenty of theories regarding the cause of periodic limb movement disorder; metabolic diseases, sleep disorders, and neurodevelopmental disorders are among them. If those theories hold true, then it stands to reason that the treatment and management of PLMD may lie in treating any underlying conditions first.

When to See a Doctor

Typically periodic limb movement disorder doesn’t disturb the person themself or cause them to wake, but it will disturb their bed partner. So, like many sleep disorders, those who suffer from periodic limb movement disorder are usually unaware of these movements until or unless a bed partner makes it known. If your PLMD is a nuisance and disruptive to your partner, you may want to see a doctor just as an act of kindness and consideration.

Moreover, if your PLMD begins to affect you, causing daytime sleepiness, fatigue, or excessive irritability, you may want to schedule an appointment with your doctor to get to the bottom of things.

Frequently Asked Questions

Is periodic limb movement disorder serious?

While PLMD is generally not considered life-threatening, it can be a serious condition that significantly impacts a person’s quality of life. People with PLMD may experience difficulty falling and staying asleep, restless sleep, and daytime fatigue. The loss of sleep from these symptoms can make it difficult to work, drive, and perform other daily activities.

PLMD may also be associated with other medical conditions, such as restless leg syndrome or sleep apnea. These conditions can further disrupt sleep and affect a person’s overall health. Speaking with your doctor about your symptoms and how they affect your life can be used to set up an appropriate treatment plan.

Is periodic limb movement disorder considered a disability?

While PLMD can be disruptive to sleep and cause daytime fatigue, it is typically not considered a disability. However, in rare cases, severe PLMD may interfere with the ability to perform a job or other expected daily activities. In these cases, it may be possible to qualify for disability benefits.

If you believe that your PLMD is interfering with your ability to work and impacting your ability to live your life, it’s important to discuss your symptoms with your doctor and a disability attorney to determine your options.

What can cause periodic limb movement disorder?

The causes of periodic limb movement disorder are still being studied. But researchers have noted several factors that contribute to the condition.

One possible cause is an imbalance in brain chemicals, such as dopamine, which can affect the muscles and lead to involuntary leg movements. Similarly, certain medications that affect the levels of brain chemicals can result in involuntary leg movements during sleep.

Additionally, certain medical conditions, such as kidney disease, anemia, or diabetes, may increase the risk of PLMD. Finally, lifestyle or sleep deprivation can factor into the development of PLMD.

How can I treat periodic limb movement disorder?

Treatment for periodic limb movement disorder typically involves lifestyle changes, medications, and therapy. People with PLMD may need to avoid caffeine to fall asleep faster at night, and engage in regular exercise for better sleep. A strict sleep schedule with a relaxing bedtime routine and consider other ways they might improve sleep hygiene.

Your doctor can work with you to consider medications for PLMD such as dopamine agonists, benzodiazepines, and anticonvulsants, along with the appropriate dosage. Cognitive-behavioral therapy or biofeedback can also help manage PLMD symptoms.

What is the difference between restless leg syndrome and periodic limb movements?

Restless leg syndrome (RLS) and periodic limb movement disorder are easy to conflate with each other. But while one individual can experience both RLS and PLMD, they are two separate conditions and have some key differences.

RLS is a neurological condition characterized by uncomfortable sensations in the legs. Typically these sensations happen in the evening or at night. People with RLS may experience aching, burning, itching, or crawling. They can feel an irresistible urge to move their legs to relieve the discomfort.

PLMD, on the other hand, is a sleep disorder characterized by involuntary leg movements during sleep. These movements can cause sleep disruption and daytime fatigue. Unlike RLS, the involuntary movements associated with PLMD do not typically cause discomfort or an urge to move the legs.

The Bottom Line

Periodic limb movement disorder is a rare condition that involves spontaneous movements during sleep. It’s marked by cramping or jerking, particularly of the lower extremities. PLMD is one of the few sleep disorders that occur while you’re sleeping. For that reason, those with PLMD are often unaware that it’s happening. Most people only find out when their partners share that information.

While the exact cause of PLMD remains yet unknown, other sleep disorders and metabolic diseases are thought to be significant risk factors. Typically polysomnograms are required to definitively diagnose periodic limb movement disorder. There is no cure per se, but like many other sleep disorders, lifestyle changes may be helpful in managing periodic limb movement disorder as well.