You’re sound asleep, and then, without warning, you wake up with a paralyzing stiffness in your calf or foot.

Whether you call it a foot or leg cramp (aka “charley horse”), it’s a common, somewhat mysterious pain that happens when a muscle gets involuntarily stiff and can’t relax.

“They tend to happen more frequently as we age,” says sports and exercise medicine physician Kim Gladden, M.D., “While they can be uncomfortable, they are rarely harmful.”

Here’s what causes these cramps, as well as tips to help prevent them.

7 COMMON CAUSES FOR CRAMPS:

Whether day or night, your foot and calf muscles can spasm or cramp. This can happen to various muscles — not just in the legs or feet — though these cramps are often most uncomfortable.

Causes for muscle cramps include:

1. Lack of hydration. “If you are experiencing cramping, it’s important to look at your hydration first,” Dr. Gladden says. You want to make sure you are drinking enough water throughout the day.
2. Problems with nutrition. While a balance of electrolytes (calcium, sodium, potassium, and magnesium) is essential for the contraction and relaxation of a muscle, it’s best not to simply self-treat with supplements. “Taking excess supplements if you don’t need them can be harmful,” Dr. Gladden says. Instead, she suggests eating a variety of foods with plenty of colorful fruits and vegetables. This includes leafy greens and fruits, including bananas, to add a balance of electrolytes to you diet.
3. Side effect of medication. Some medications such as statins and furosemide (Lasix®) can also cause muscle cramps. A tip-off is when cramps start suddenly after you begin taking a new medication. If this happens, see your practitioner.
4. Not stretching enough. Taking time to stretch each day, including after a brief warm up or after a shower can help. “You want your muscles to be as strong and supple as they can be. Adequate stretching after a brief warm-up period is key to this,” Dr. Gladden says.
5. Overexertion. If you exercise harder than usual or experience muscle fatigue, this can cause cramps. Pace yourself.
6. Poor circulation. If you have cramping that increases when you walk, it could be a problem with your circulation. “Some circulation problems cause pain that feels like cramping. If it gets worse when you walk, or if you have cramps that just don’t stop, definitely see your doctor,” Dr. Gladden says.
7. The wrong shoes. A less-known cause for muscle cramping: your shoes. “You want to look at your shoes, especially if you changed from flats to heels. This also can cause cramps,” Dr. Gladden says.

How to stop leg and foot cramps

There are some simple ways to respond to leg and foot cramps:

• If it happens while you are lying down or in bed, try to simply stand up and put some weight on the affected leg or foot. This can sometimes be enough to stop that tender stiffness.
• Use warmth/heating pads to increase blood circulation to the muscle and to relax it. Soaking in a warm tub of Epsom salt can also help ease the tension.
• For more stubborn pain, you can try a non-steroidal anti-inflammatory medication, such as ibuprofen.

Easy stretches to keep calves and feet happy

Here are some simple stretches that can help stop pain and prevent it.

Basic calf stretch

This calf stretch is commonly used by runners. Here’s how to do it:

1. Stand with your palms placed against a wall, with arms stretched out
2. Step back with leg of affected calf
3. Lean forward on the other leg and push against the wall

You should feel a stretch in your calf muscle and the back of the leg.

Towel stretch

Do this stretch while you sit:

1. Keep legs outstretched in front of you
2. Point the toes of your affected foot at the ceiling so that the leg is engaged
3. Take a towel or neck tie and wrap it around your foot, holding it with both hands
4. Lift the leg slightly until you feel a good stretch

Keep cramps from happening again

Here are some tips to prevent leg cramps:

• Stay well hydrated
• Stretch each day, especially before you exercise
• Limit or avoid alcohol
• Eat a balanced diet that includes natural sources of calcium, potassium and magnesium
• Increase your activity level gradually

If leg or foot cramps are occasional occurrences, you can generally manage them yourself. However, if they happen frequently, are severe, or if you are concerned any of your medications are the culprit, talk to your doctor. They could signal a medical problem that requires treatment.