Periodic Leg/Limb Movement Disorder (DD) and Restless Legs Syndrome (RLS)

When PLMD and RLS kick in together, how do you keep them still?

Periodic Leg/Limb Movement Disorder (PLMD) implies involuntary disturbing movements; Restless Legs Syndrome (RLS) is uncomfortable sensations.

PLMD occurs while we are asleep, RLLS when we are awake, resting or falling asleep.

Though very different, PLMD and RLS are often confused, probably because they often turn up together and share certain resemblances:

  • Both affect the limbs, usually the legs.
  • They can start at any age, but more often after 50 years old.
  • They may be linked to iron and ferritin deficiencies.
  • Symptoms may disrupt sleep. RLS may interfere with falling asleep and PLMD may disrupt sleep, and in turn, can cause sleep deprivation and insomnia symptoms with associated daytime consequences such as daytime itself.
  • They are treated similarly.

This table can help you tell apart PLMD and RLS:

Characteristics of Periodic Leg/Limb Movement Disorder (PLMD) Restless Legs Syndrome (RLS)
Main symptoms
Involuntary movements during sleep of the limbs, mainly of the legs, often described as a twitch, kick, jerk or upward flexing of the feet
• The movements are repetitive and at recurring intervals (periodic).
• Periodic movements do not always wake people, as most of the time they are unaware of them. Bed partners can be more disturbed by them than the sleepers. Some people report that they have trouble falling and staying asleep because of it.
• About 50% have RLS as well.
• The restless feeling is unpleasant and uncomfortable. Many people have trouble describing it.
• Reports include sensations of: o An irresistible urge to move the legs. May occasionally affect the arms.
o Creeping
o Crawling
o Tingling
o Burning
o Itching
o Aching
o Electrical discharges
o Need to move

• Voluntary movements relieve, in part or in whole, the urge and unpleasant sensations. So to get relief, people often pace or walk, stretch or jiggle their legs, or toss and turn. Relief is usually brief as symptoms often return.
• About 80%–90% have PLMD symptoms as well.
When does it occur?
• While asleep.
• When falling asleep and before REM sleep occurs.
• While at rest or falling asleep, hence restless legs while awake.
After sitting or lying down for an extended period, e.g. after a long car ride or plane trip, at the theatre or movies or while watching TV or working at the computer.
• Occurs or worsens more frequently in the evening or at night when resting or falling asleep. Can interfere with sleep. For example, if it occurs while trying to fall asleep, RLS symptoms can make it hard to fall and stay asleep.
Who is affected
Predominantly during early childhood (preschoolers) but seen in all ages.
Predominantly during childhood (school age) but seen in all ages.
Who gets it?
• May develop at any age, but it is most likely in older adults.
• Most common in people over the age of 65 (nearly 50% experience it).
• May develop at any age.
• RLS cases increase with age, making it much more common in older adults.
Women are more affected than men.
Pregnant women are often affected.

What to do or not do?

It depends mostly on how much suffering these conditions cause you. Do you find them distressing? Are the symptoms causing disturbances at night or during the day? If so, it’s good to keep in mind that there is almost always a solution. Symptoms can be managed by behavioural adjustments, lifestyle changes and/or medication.

Many people will experience restless leg (RLS) or periodic movement (PLMD) symptoms on an irregular basis or without a major impact  on their quality of life. That’s why the public and healthcare professionals can often overlook these conditions. On the other hand, those of you who experience frequent and severe symptoms that disrupt your daily routine and your sleep quality, can attest to what a burden these conditions can be. If you are suffering and these conditions are interfering with your life, treatment should be considered to regain control over your night and day. Another reason to seek treatment is that these lifelong conditions are known to worsen with age.

Here’s how treatment works: Just as for many other sleep-related conditions, it is important to assess general health with a medical exam and a lifestyle assessment to understand the causes and get proper treatment. A blood test that includes ferritin levels is mandatory to determine an iron deficiency.

Sleep studies are as crucial as the medical exam, especially if periodic leg movement is suspected while asleep. They are the next course of action to continue the eliminatory diagnosis process and exclude other sleep disorders.

Sleep studies are a combination of subjective and objective sleep assessments done at the sleep clinic at your convenience by sleep professionals. They could include questionnaires, keeping a sleep journal and evaluating overall sleep quality using diverse physiological tests.

Your sleep quality and architecture will be recorded using a polysomnogram (PSG). This non-painful test uses multiple electrodes resting on your skin to measure electrical brain and muscle activities while you sleep. Sleep studies often test your breathing and lung function as it can explain several daily symptoms of poor sleep. To do so, respiratory rates and oxygen levels are recorded with a nose cannula, an effort belt is placed over your chest and abdomen and a heart rate and oxygen sensor at the tip of one of your fingers.

For more information on sleep studies, please consult the Canadian Sleep Society (CSS) patient guide:

After diagnosis, treatment depends on how distressing the symptoms are for you. Once that is determined, treatment focuses on symptom management with lifestyle and behavioural changes and medication.

Lifestyle and behavioural changes involve reducing or eliminating the use of potential triggers such as tobacco, alcohol or caffeine. Exercise, relaxation techniques and meditation are non-pharmacological options. On the spot interventions consist of massaging the legs, taking a hot bath or moving, for example stretching or walking around. If not already in place, a regular sleep schedule should also be established.

In general, the medication used to treat PLMD or RLS symptoms acts on the brain chemistry involved in movement regulation. A target of choice is a substance involved in brain cell communication (i.e.: neurotransmitter) called dopamine. Medications such as benzodiazepines are also prescribed to act on abnormal movement-related brain activity. Iron supplements can manage the symptoms if an iron deficiency is detected in the blood test.

What are the causes of PLMD and RLS?

Periodic limb/leg movement disorder (PLMD) like restless legs syndrome (RLS) is either idiopathic, the medical term for without a known cause, or secondary to a medical condition or related to medication/drug use.

Idiopathic PLMD or RLS often run in families, pointing to a genetic link that increases the chances of being affected by either one of these conditions. Several possible genes are currently under investigation.

Since dopamine-related medications dramatically improve symptoms, a neurochemical imbalance involving this cell communication chemical may have a causal effect. Some of you may know that the neurotransmitter dopamine is also associated with Parkinson’s disease, but no link has been found between these sleep conditions and Parkinson’s. So it appears that the causes are not in the limbs per se, but in our genes and how our brain regulates neurochemicals involved in movement such as dopamine.

Secondary PLMD or RLS is caused by another disease or condition or, sometimes, from taking medicaments or drugs. Symptoms usually go away when the condition improves or the person stops taking the medication.

Several antidepressants, antihistaminic and certain antipsychotics may have PLMD or RLS as side effects. If you take anti-dopaminergic agents, a doctor may need to monitor them, as they are primary suspects in secondary PLMD/RLS.

Pregnancy and anemia may cause an imbalance in iron levels, which can be secondary causes of PLMD or RLS. Symptoms of these conditions can also be a consequence of diabetes and kidney disease.

What are the consequences of PLMD and RLS?

While periodic limb/leg movement disorder (PLMD) like restless legs syndrome (RLS) on their own are not medically dangerous conditions, they can make life very unpleasant.

If you suffer from PLMD and maybe RLS, with severe and frequent symptoms, you may experience daytime sleepiness, fatigue or feeling unrested when you awake. Their symptoms may also lead to chronic insomnia by affecting the time it takes to fall asleep or maintain sleep and in turn, hamper sleep duration and quality.

This can cause sleep deprivation, with health consequences ranging from lacking focus or being moody to an increased risk of cardiovascular diseases or depression, for example.

PLMD, like RLS, can also be an indicator of more serious underlying medical conditions such as diabetes, kidney disease and anemia.

Given that they may be red flags for other illnesses and the fact that symptoms are manageable, think about getting medical advice to regain restful nights and days.