What are periodic limb movements?

Periodic limb movements are when you have episodes of simple, repetitive muscle movements. You are unable to control them. They usually do not keep you from falling asleep. Instead, they can disrupt your or your bed partner’s sleep during the night. This can cause you both to be very tired during the day.

Periodic limb movements do not involve a change in body position, stretching a muscle, or a cramp. Instead, the movements tend to involve the tightening or flexing of a muscle. They occur most often in the lower legs. They can occur at two different times:

Periodic limb movements while you sleep
Periodic limb movements while you are awake

Limb movements during sleep are much more common. When they occur often through the night, they can disrupt your sleep many times. Normally, you are unaware of the movements or of waking up.

A typical movement is for the big toe to extend. Often the ankle, knee or hip will also bend slightly. Though it is less common, this can also happen in your upper arms.

The degree to which these movements occur can change from night to night. They usually happen during non-rapid eye movement sleep in the first half of the night. When these movements are very severe, then they may also happen while you are awake.

An episode will normally last from a few minutes to an hour. Within that time, movements tend to occur every 20 to 40 seconds. They may affect only one of the legs. More often, they will affect both legs.

Limb movements during sleep are quite common. For most people, the movements do not disturb their sleep in a significant way. This means that it is not a sleep disorder. The sleep of the bed partner tends to be affected more often than that of the patient.

The movements reach the level of a disorder, periodic limb movement disorder, when they disrupt the patient’s sleep and daily life.

This disorder may be a factor in causing you to have any of the following:

Depression
Bad memory
Short attention span
Fatigue

What are symptoms of periodic limb movements

Normally, you are unaware of the movements. This can make it very hard for you to know if you have periodic limb movements. Someone who sleeps in the same bed with you would be more likely to notice the movements. You might have periodic limb movement disorder if:

Someone else told you that your body makes unusual, repetitive movements while you sleep
These movements tend to occur in your lower legs
You feel like you are never well-rested, even after a full night of sleep
You are often very tired during the day

It is also important to know if there is something else that is causing your sleep problems. They may be a result of one of the following:

Another sleep disorder (for example, restless legs syndrome or sleep apnea)
A medical condition
Medication use (for example, anxiety and depression medications)
A mental health disorder
Substance abuse

What are risk factors for periodic limb movements?

Periodic limb movement disorder occurs in both children and adults. The chance of having it increases with age, making it very common in the elderly. It occurs in up to 34% of people over 60 years old. Studies have not yet shown how common it is in other age groups.

No difference has been noticed in the rate of males and females who have it. The family pattern has not been studied in detail.

Periodic limb movement during sleep can be influenced and caused by several factors. They are commonly found in people who have one of three other sleep disorders:

Low brain iron may play a role in making them worse.

High rates of limb movements during sleep have been found in some people with:

Spinal cord injury
Multiple system atrophy (a rare neurological disorder)
Sleep-related eating disorder

The following medications are thought to cause limb movements during sleep or make them worse:

Some antidepressants
Lithium
Dopamine-receptor antagonists (for example, some anti-nausea medications)
Antihistamines or allergy medications

Data is less clear about a link between limb movements and the following:

Kidney disease
Parkinson disease
ADHD
Pregnancy
Posttraumatic stress disorder
Multiple sclerosis

How to diagnose periodic limb movements?

For most people, the movements do not disturb their sleep in a severe way. They do not need to seek medical help. In other cases, severe movements can greatly disturb your sleep and life. In this case, you will want to see a sleep doctor.

You should complete a sleep diary for two weeks. This will give the doctor clues as to what might be causing your problems. You can also rate your sleep with the Epworth Sleepiness Scale. This will help show how your sleep is affecting your daily life. The doctor will need to know your complete medical history. Be sure to inform her of any past or present drug and medication use. Also, tell her if you or a relative have ever had a sleep disorder.

Your doctor will likely have you do a sleep study. This is called a polysomnography. The test records your brain waves, heart rate, and breathing as you sleep. It also monitors how your arms and legs move. Not only will it keep track of your movements, but it will also help detect any other sleep disorder that you may have.

How to treat periodic limb movements?

When it is necessary to treat periodic limb movement disorder, the same drugs that are used for restless legs syndrome also work. These include drugs that replace a chemical in the brain called dopamine. These drugs are also used to treat Parkinson’s disease. However, if you have periodic limb movement disorder, you are not at an increased risk of getting Parkinson’s disease. Other medications used include the following:

Sleeping tablets
Some anti-seizure medications
Narcotic pain killers

Low iron levels have been associated with periodic limb movements during sleep. Your doctor may recommend a blood test to check your iron levels and if low, an iron supplement may be recommended.