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Nighttime leg cramps are different from another common nighttime leg problem called restless legs syndrome. With restless legs syndrome, your legs feel fidgety or crawly unless you move them. For more information, see the topic Restless Legs Syndrome.

What are nighttime leg cramps?

Nighttime (or nocturnal) leg cramps are usually sudden spasms, or tightening, of muscles in the calf. But the muscle cramps can sometimes happen in the thigh or the foot. They often occur just as you are falling asleep or waking up. These painful cramps can last a few seconds to a few minutes.

These leg cramps are also called charley horses.

What causes nighttime leg cramps?

Though nighttime leg cramps are common, experts don't know exactly what causes them. But most of the time it is not because of illness. Some of the things that may cause leg cramps include:

• Getting too much exercise or overusing the muscles.
• Standing on concrete for a long time, sitting for a long time, or putting your legs in awkward positions while you sleep.
• Not having enough potassium, calcium, and other minerals in your blood.
• Being dehydrated, which means your body has lost too much fluid.
• Taking certain medicines, such as antipsychotics, birth control pills, diuretics, statins, and steroids.
• Having flat feet.
• Having thyroid disease.

How can you stop a nighttime leg cramp when it happens?

You may need to try several different ways to stop a leg cramp before you find what works best for you. Here are some things you can try:

• Walk around, or jiggle your leg.
• Stretch your calf muscles. You can do this stretch while you sit or stand:
  • While sitting, straighten your leg and flex your foot up toward your knee. It may help to place a rolled towel under the ball of your foot and, while holding the towel at both ends, gently pull the towel toward you while keeping your knee straight.
  • While standing about 2ft from a wall, lean forward against the wall. Keep the knee of the affected leg straight and the heel on the ground. Do this while you bend the knee of the other leg. See a picture of how to do this calf stretch.
  These exercises stretch your calf muscles, and you will probably feel the leg cramp go away after a few minutes.
• Some people find that a hot shower or a warm bath helps. Others get relief by rubbing the calf with an ice pack.

How can you prevent them?

Use these tips to help prevent nighttime leg cramps:

• Drink plenty of water and other fluids during the day.
• Limit or avoid drinks with alcohol or caffeine. These can make you dehydrated, which means your body has lost too much fluid.
• Make sure you are eating healthy foods (especially if you are pregnant) that are rich in calcium, potassium, and magnesium.
• Ride a stationary bike to condition and stretch your muscles.
• Stretch your leg muscles for a few minutes before you go to bed.