Periodic Limb Movements of Sleep (PLMS) Overview

Periodic limb movements of sleep (PLMS) is one of the sleep disorders that may cause disruptive movement of your legs, much like restless legs syndrome (RLS). What is PLMS? Learn how movements of the legs at night may relate to other sleep disorders and lead to sleep disruption, insomnia, and even daytime sleepiness.

Defining Periodic Limb Movements of Sleep (PLMS)

Periodic limb movements of sleep (PLMS) consist of sudden jerking movements of the legs which occur involuntarily during sleep and which the affected individual may remain unaware. It may involve kicking, twitching, or extension of the legs. Importantly, restless legs syndrome (RLS) symptoms are noted during wakefulness while PLMS occur during sleep.

The movements associated with PLMS often consist of flexion or extension at the ankle. In some cases, this may also occur at the knee. It may occur on one side or alternate back and forth between the left and right sides.

It tends to increase with age and often, but does not always, accompanies restless legs symptoms. If PLMS causes daytime impairment such as excessive daytime sleepiness or significant sleep disruption and insomnia (even to a bed partner), it may be termed periodic limb movement disorder (PLMD).

Diagnosis

The gold standard for diagnosis of PLMS is a sleep study called a polysomnogram. As part of this study, superficial electrodes are placed on the legs and sometimes even the arms. These are able to detect any muscle contraction or movements.

In individuals with PLMS, there will be repetitive movements (at least four in a row) that may last from 1/2 second to 5 seconds. If these movements occur more than 15 times per hour in adults or 5 times per hour in children this is abnormal.

If the movements are associated with arousals or awakenings from sleep, they may be more significant. They also may be deemed important if they become disruptive to the bed partner. When they are noted in isolation on a sleep study without associated symptoms or impacts, no further treatment may be necessary.

If the movements cannot be explained by another disorder, PLMS may be the likely diagnosis. Again, if the movements lead to sleep disruption, insomnia, and excessive daytime sleepiness, it is called PLMD.

Isolated PLMS noted on a sleep study, without consequence, are not significant and do not require treatment with medication. RLS is diagnosed based on clinical criteria (an uncomfortable feeling often noted in the legs associated with an urge to move that occurs in the evening when lying down and is relieved by movement) and no testing is required to diagnose that condition.

Treatment

In general, it is not necessary to treat PLMS if the person affected does not have any complaints of sleep disruption. If it causes partial or total arousal from sleep, contributing to insomnia or undermining sleep quality, then treatment can be considered. Also, if the movements are disruptive to a bed partner, it may also be desirable to get them under control.

Prescription medications can be effective in treating PLMS. Many of the drugs used to treat RLS are also helpful. These may include benzodiazepines (often clonazepam), Mirapex (generic name pramipexole), and Requip (generic name ropinirole). These movements may also occur in relation to obstructive sleep apnea events, and then the treatment would target the breathing disorder.

A Word From Verywell

If your leg movements are disruptive to you at night, you should make an appointment to see a sleep specialist and have your condition properly evaluated. After a diagnostic study, the cause can be properly identified and the appropriate treatment may be pursued. As movements may also occur secondary to breathing events, it will be necessary to ensure that sleep apnea is not causing the disruption. Fortunately, effective treatment options can calm legs down at night and lead the rest that you need to function at your best.