Periodic limb movements of sleep (PLMS) is a sleep disorder that involves repetitive and involuntary movements of the limbs.
Periodic limb movements occur when the arms or legs move during sleep. In many cases, periodic limb movement is not a cause for concern.
However, if periodic limb movements are causing issues for the person or their bed partner, they may want to seek treatment options.
Keep reading to learn more about the symptoms and treatment options associated with PLMS.
Periodic limb movements can occur during waking hours and during sleep. According to the American Academy of Sleep Medicine (AASM), periodic limb movement during sleep is more common.
The National Sleep Foundation define PLMS as repetitive movements that occur most often in the legs and feet every 20–40 seconds. The movements often cluster into periods of a few minutes to several hours.
PLMS usually involves flexing the limbs during sleep, typically during periods of non-random eye movement (REM) sleep. These movements usually occur in the lower limbs, such as extending the big toe or bending the ankles, knees, or hips. Though less common, some people may experience movements in their arms.
People with PLMS may be unaware of the condition. It is most often their bed partner who will report the limb movements.
PLMS can also occur in conjunction with other sleep disorders, such as restless legs syndrome (RLS).
PLMS vs. RLS
Several similarities exist between PLMS and RLS, especially regarding symptoms and treatment. In fact, some people consider them to be part of the same condition.
People with RLS experience twitching and discomfort in their legs, usually around bedtime or when trying to rest. This can disrupt sleep and result in insomnia.
The main difference between the two conditions is that PLMS only occurs during sleep, while RLS can happen when a person is either awake or asleep.
An older study suggests that approximately 80–90% of people with RLS have PLMS.
The exact cause of PLMS is unknown. One theory is that difficulties with nerve regulation may be an underlying cause, but no studies have come to a firm conclusion.
Although anyone can develop PLMS, the AASM suggest that the likelihood of having it increases with age, as it occurs in up to 34% of people over the age of 60. The condition affects males and females equally.
PLMS seems to be more common in people with the following medical conditions:
- REM sleep behavior disorder
- iron deficiency
- spinal cord injury
- multiple system atrophy
- sleep-related eating disorder
Researchers have also linked some medications to PLMS, including antidepressants and antinausea medications.
It is common for people with PLMS to not experience any symptoms.
They may not feel the movements or be aware of their actions during the night. Instead, a person’s bed partner may notice that they kick or move around during the night and disturb their sleep.
In some cases, however, a person may wake up due to the movements. An uncomfortable sensation may occur in the calves or thighs, either before falling asleep or during the night, when the movement wakes the person.
Some symptoms that may occur due to PLMS include:
- poor sleep
- daytime sleepiness
PLMS may also be a contributing factor toward:
- short attention span
- poor memory
A doctor may suspect PLMS if the person has significant sleep disruption as well as issues with related daytime functions, such as mood, memory, and cognitive functioning.
The doctor may initially carry out a physical examination. They may also take a full medical history and ask about any medications the person is taking, their family medical history, and certain lifestyle factors.
A doctor may also suggest that the person completes a sleep diary before the examination.
They will attempt to rule out other sleep disorders that may cause similar issues. These include RLS and narcolepsy.
A polysomnogram (PSG) is the primary method of diagnosing PLMS. A PSG is a sleep study that can provide detailed information about a person’s sleep, including the duration and quality.
A person does not usually need to treat their PLMS. They will only need treatment if PLMS is disturbing their sleep.
In many cases, doctors will recommend limiting caffeine consumption, as caffeine may make the symptoms worse.
When the doctor suspects that an underlying condition is causing PLMS, they will attempt to address that condition. For example, if certain medications are responsible, a doctor may consider prescribing a different type.
Medications and supplements are available to help treat PLMS. Many of these medications can also help treat RLS. These include:
- dopamine agonists
- GABA agonists
- anticonvulsant agents
- iron supplements
A person can talk to their doctor if:
- their movements are waking them up at night
- their movements are disturbing their partner’s sleep
- PLMS is affecting other aspects of their lives
A doctor can diagnose PLMS and recommend an appropriate treatment. They can also help a person determine whether or not another condition is causing their sleep condition.
A person with PLMS may not need any medical treatment. Often, a person does not even know that they have the condition.
Typically, they may only discover they have PLMS if they wake their partner or frequently notice that they have kicked the sheets off at night.
At other times, a person may wake up with some discomfort in their lower legs.
If sleep disruption occurs, a person may notice symptoms such as daytime sleepiness, moodiness, or difficulty concentrating. If the symptoms are negatively affecting a person’s life, it is important to see a doctor.
For many people, PLMS does not significantly affect their sleep. For others, however, it may cause daytime sleepiness or disrupt their bed partner’s sleep.
Treatment often consists of limiting caffeine and increasing iron intake. In some cases, a doctor may prescribe medication to help treat the underlying condition or any other related conditions, such as RLS.