Most of the time, muscles do not move unless the brain signals for them to do so. However, these signals sometimes get mixed up. The mix-up may occur in the brain, the nerves that send the signals, or the muscles that receive them.
When signal misfires occur, the muscles can move involuntarily, which people usually refer to as a twitch. Twitching is the result of the sudden contraction or release of a muscle. Doctors may use the term “myoclonus” to describe these fast, involuntary twitches.
In this article, we outline the types of muscle twitches that may occur in the legs and how they might feel. We also list some possible causes of leg twitches, along with information on how doctors diagnose and treat them.
Physiologic myoclonus can affect people with a good health status, and it usually does not require treatment. Examples of physiologic myoclonus include:
- leg twitching when falling asleep
- physiologic startle responses
Pathologic myoclonus refers to myoclonus that is either a symptom of an underlying medical condition or a reaction to a particular medication.
Pathologic myoclonus can involve persistent muscle contractions that may affect an entire group of muscles or muscles in different parts of the body. Severe cases may affect a person’s movement and mobility.
A person who develops a twitch in their leg usually notices when it is happening. The twitches may be irritating, but they are not usually painful.
However, muscle twitches in the legs can sometimes trigger muscle cramps. Cramps are very common, affecting roughly 60% of adults from time to time.
Depending on the cause of the leg twitching, a person may experience additional symptoms, such as:
- crawling or fizzing sensations
- muscle spasms in the affected area
- a feeling similar to a shudder rippling through the body
It is very common for people to experience occasional bouts of leg twitching. We outline two common causes of leg twitching below.
The medical term for repetitive involuntary muscle twitching is benign fasciculation. It affects about 70% of the general population and is rarely associated with serious nervous system disorders.
Some possible causes of benign fasciculations in generally healthy people include:
- stress or anxiety
- physical exhaustion and lack of sleep
- overconsumption of alcohol, or alcohol withdrawal
- overconsumption of caffeine, or caffeine withdrawal
- low blood sugar
- nutrient imbalance
- hormone imbalance
- use of certain medications
Restless leg syndrome
Restless leg syndrome (RLS) is a condition in which a person experiences uncomfortable sensations in their legs. An irresistible urge to move the legs often accompanies the sensations.
About 80% of people who have RLS also experience leg twitching while they sleep. The medical term for this is periodic limb movements of sleep.
Restless leg syndrome is common, affecting up to 1 in 10 people at some point in their lives.
In most cases, leg twitching is due to a common and relatively benign cause.
However, persistent or frequent leg twitching can sometimes signal an underlying nervous system disorder, such as:
A doctor will typically diagnose the cause of leg twitching by:
- taking a complete medical history
- gathering specific information about the twitching, such as:
- where it happens and how long it lasts
- whether it affects other parts of the body
- when it happens
- looking for signs of toxicity due to:
- medication use
- illicit drug use
- environmental hazards
In some cases, a doctor may order one or more of the following diagnostic tests:
- Electromyography (EMG): A test that records electrical activity in the skeletal muscles. Doctors use EMG to assess the condition of the muscles and the nerves that innervate them.
- Electroencephalogram: A test that detects and records electrical activity in the brain.
- MRI scan: A medical imaging test that allows the doctor to view nerves and other soft tissues inside the body. It can also help them detect lesions that may be the cause of involuntary twitching.
- Blood tests: Certain blood tests could help identify underlying medical conditions that may be responsible for the symptoms.
People who experience occasional leg twitching may be able to manage the condition by making certain lifestyle changes. Examples include:
- staying well-hydrated
- eating a healthful, balanced diet
- cutting down on stimulants, such as caffeine and alcohol
- quitting smoking, if applicable
- exercising regularly
- stretching and massaging the legs gently
- getting plenty of rest
People who suspect that their leg twitching is due to a medication should not stop taking it unless their doctor advises them to do so.
If leg twitching is due to an underlying medical condition, treating the condition should help reduce the frequency of the twitching, its severity, or both.
Most of the time, leg twitching is a response to specific circumstances, such as exhaustion, dehydration, or the use of stimulants, such as caffeine or alcohol.
However, twitching can also be a sign of a serious underlying medical condition. People should see a doctor if the:
- leg twitches do not get better following appropriate lifestyle changes
- leg twitches persist for more than 2 weeks
- twitching starts when the person is resting
- twitching begins after the person starts taking a new medication
- twitching affects more than one part of the body
- twitching occurs alongside any of the following symptoms:
Leg twitching is a common symptom that is most often due to lifestyle factors, such as overexertion, dehydration, or overuse of stimulants. It usually gets better following appropriate lifestyle changes.
However, twitching can sometimes be a symptom of a serious underlying medical condition, such as a nervous system disorder. A person should see a doctor if their leg twitching persists, worsens, or occurs alongside other worrying symptoms.