Periodic Limb Movements of Sleep (PLMS)


What is PLMS?
Periodic Limb Movements of Sleep (PLMS) is when your legs or arms move when you're asleep. It happens every 10 to 60 seconds and is out of your control. There are various ways this can happen such as flexing of the toe or foot, bending of the ankle or knee or twitching of the hip. This tends to occur over and over. It can last from a few minutes to a few hours. PLMS is mainly seen in the first third of the night, during the deepest type of sleep.

Often, the way people know that they have PLMS is when their bed partner complains of being kicked. The blankets may be all over the place in the morning. Some people may move their legs in this way hundreds of times per night. In some cases this can disrupt the sleep of the person with PLMS or that of their bed partner. For others, PLMS may not be a problem at all. It only needs to be treated if it is causing a problem.

How common is PLMS?
PLMS is more common in older age. It affects only 2% of people aged less than 30, 5% of 30 to 50 year olds, and 25% of those between 50 and 60 years old. About 40% of people 65 or older may have PLMS. Both men and women have the same chance of getting it.
As many as 80% of people with Restless Legs Syndrome also have PLMS. These problems mean they may find it hard to both fall asleep and stay asleep and they may feel fatigued or sleepy during the day.

How do I know if I have PLMS?
This can be tested with an overnight Sleep Study. Leads are put on the legs and/or arms while sleep is measured. In some cases, records may be made over a longer period of time (1-2 weeks). In this case a monitor is worn around the ankle and/or wrist.

What causes PLMS?
The problem originates in the nervous system. The exact cause is not yet known.

How can PLMS be treated?
PLMS can disrupt sleep. This can interfere with how you function during the day by making you tired. If so, you need to consider treating it. The same drugs that are used to treat Restless Legs Syndrome may be used. Cutting down on caffeine, alcohol, and smoking can also help.

Is PLMS the same as myoclonus?
In the past, PLMS has had other names e.g. restless legs, nocturnal myoclonus, periodic leg movements and periodic limb movement disorder. The usual name now is Periodic Limb Movements of Sleep.

How can I get help?
If you are worried about PLMS, you should consult your GP. If required they can refer you to a Sleep Specialist.

Where can I get further information?

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