Night leg cramps, also called nocturnal leg cramps, are painful, involuntary contractions or spasms of muscles in your legs, usually occurring when you're in bed. Night leg cramps usually involve your calf muscles, although muscles in your feet or thighs might cramp as well. Forcefully stretching the contracted muscle relieves the pain.

Most of the time, no apparent cause for night leg cramps can be identified. In general, night leg cramps are likely to be related to muscle fatigue and nerve problems.

The risk of having night leg cramps increases with age. Pregnant women also have a higher likelihood of having night leg cramps.

Several conditions, such as kidney failure and diabetic nerve damage, are known to cause night leg cramps. But if you have one of these, you're most likely aware of it and have symptoms other than night leg cramps.

People who are taking certain medications, such as certain diuretics, might be more likely to have night leg cramps, although it's not known if there's a direct connection.

Restless legs syndrome (RLS) is sometimes confused with night leg cramps, but it's a separate condition. In general, pain is not a main feature of RLS, although some people describe their RLS as being painful.

Other conditions that may sometimes be associated with night leg cramps may include:

Structural disorders

• Peripheral artery disease (PAD)
• Spinal stenosis

Metabolic problems

• Acute kidney failure
• Addison's disease (adrenal insufficiency)
• Anemia
• Chronic kidney disease
• Cirrhosis (scarring of the liver)
• Hyperthyroidism (overactive thyroid)
• Hypothyroidism (underactive thyroid)
• Type 1 diabetes
• Type 2 diabetes

Medications and procedures

• Blood pressure drugs
• Cholesterol-lowering drugs (statins)
• Dialysis
• Diuretics (water retention relievers)
• Oral contraceptives

Other conditions

• Dehydration
• Diarrhea
• Muscle fatigue
• Nerve damage, as from cancer treatments
• Osteoarthritis (disease causing the breakdown of joints)
• Parkinson's disease
• Pregnancy

For most people, night leg cramps are merely an annoyance — something that jerks you awake infrequently. But in some cases, you may need to see a doctor.

Seek immediate medical care if you have

• Severe and persistent cramping
• Night leg cramps after being exposed to a toxin, such as lead

Schedule an office visit if you

• Have trouble functioning during the day because leg cramps interrupt your sleep
• Develop muscle weakness and atrophy with leg cramps

Self-care

Activities that might help prevent night leg cramps include:

• Drinking plenty of fluids to avoid dehydration
• Stretching your leg muscles or riding a stationary bicycle for a few minutes before you go to bed
• Untucking the bed covers at the foot of your bed

Activities that might help relieve night leg cramps include:

• Flexing your foot up toward your head
• Massaging the cramped muscle with your hands or with ice
• Walking or jiggling the leg
• Taking a hot shower or warm bath

Although once widely used, the medication quinine is no longer recommended because of risks associated with its use.