Nighttime Leg Cramps

Nighttime leg cramps, also called nocturnal leg cramps, are quite common.  Up to 60% of adults report that they have had leg cramps at night.  Up to 20% of people who experience leg cramps at night will have daily symptoms that are bothersome enough for them to see a doctor.  These leg cramps can be quite painful and can interrupt sleep.  There are a number of possible causes of these painful cramps.  You might be surprised to hear the things that do not cause these cramps.

What is a nocturnal leg cramp?

Nocturnal leg cramps are painful, involuntary contractions or spasms of muscles in your legs, usually occurring when you are in bed.  They usually involve the calf muscles but will commonly involve your feet or your thighs as well.  They can be incapacitating and last an average of nine minutes per episode.  The acute cramping may sometimes be followed by hours of recurrent cramping and residual pain.  They can cause involuntary movement of your leg, such as extreme pointing of your toe.

What causes nighttime leg cramps?

Unfortunately, we don't know the precise cause of nocturnal leg cramps.  Several possible causes have been suggested over the years, but most cases of nocturnal leg cramps turn out to have no known cause, even after a thorough investigation.  Here are a few possible causes:

• Muscle fatigue - Recent research suggests that muscle fatigue is the primary cause of leg cramps.  Research done with endurance athletes shows that a higher-than-normal intensity of exercise is associated with leg cramps.  
• Abnormal nerve function - Due to certain types of nerve damage.
• Metabolic problems - Abnormal levels of phosphate in the blood seen in patients with end-stage kidney disease on dialysis.  
• Certain medications - Including intravenous iron treatments, certain estrogens, raloxifene (Evista), naproxen, and teriparatide (Forteo), although, the overall incidence of leg cramps with these medications is relatively low.
• Pregnancy - Can be associated with leg cramps with certain activities or positions as well as nighttime leg cramps.
• Restless Legs Syndrome (RLS) - Usually causes an irresistible urge to move or shake the legs and does not cause pain or tight muscles, but studies show patients have difficulty distinguishing typical RLS symptoms from nocturnal leg cramps.

There are several medical conditions that can be associated with leg cramps in general, although they usually also cause leg cramps during the day or with activity.  Your doctor might want to rule out these conditions, depending on your medical history and symptoms.  These conditions include:

• Vascular disease such as peripheral artery disease or venous insufficiency
• Degenerative Disc Disease of the lumbar spine with spinal stenosis
• Kidney disease
• Cirrhosis of the liver
• Thyroid disease
• Neurologic conditions such as neuropathy or Parkinson's disease

What does NOT cause typical nighttime leg cramps?

Although people commonly think about the following things as being a cause of leg cramps, the clinical research has shown that these things are NOT associated with typical nighttime leg cramps:

• Dehydration
• Abnormal levels or changes in the levels of potassium, magnesium, sodium, calcium, zinc, glucose, bilirubin, or albumin (a measure of protein stores).
• Diuretics (water pills)

What can you do about nighttime leg cramps?

No current treatments for leg cramps have been proven to be both safe and effective.  However, there are a few things that you can do that might help.

For prevention you can try:

• Gentle stretching of your calf muscles before bed (slow gentle stretching, not bouncy stretching)
• Mild exercise shortly before bed such as riding a stationary bike or walking on a treadmill at a slow pace
• If muscle fatigue is an issue, changing your daily exercise routine might help
• Untucking the bed covers at the foot of your bed
• If none of these work, a mild muscle relaxer at bedtime might be helpful

For treating an acute leg cramp, you can try:

• Forceful stretching of the calf muscle by pulling the foot up toward your head
• Massaging the cramped muscle with your hands or with ice
• Walking or shaking out the leg
• Taking a hot shower or warm bath  

What should not be used to prevent or treat nighttime leg cramps?

Quinine was once used for nocturnal leg cramps, but research shows that it is only slightly beneficial.  It also has multiple dangerous drug interactions and potential serious adverse reactions.  For these reasons, it is no longer recommended.  In 2010, the US FDA issued a warning about the use of quinine, noting that the potential for serious adverse effects outweighs the modest benefit of the drug.

If you have any questions about leg cramps, please log into your account and send us your question. We are here to help.

Dr. Anita Bennett MD - Health Tip Content Editor