Most of the time, there's no known cause for night leg cramps. In general, they're likely the result of tired muscles and nerve issues.

The risk of having night leg cramps increases with age. People who are pregnant also are more likely to have night leg cramps.

Kidney failure, diabetic nerve damage and issues with blood flow are known to cause night leg cramps. But if you have one of these conditions, you probably already know. And you are likely to have symptoms other than just night leg cramps.

People who take medicines that increase urine output might be more likely to have night leg cramps. But it's not known if there's a direct link.

Restless legs syndrome is sometimes confused with night leg cramps. But the conditions are different. The most common symptom of restless legs syndrome is the need to move the legs when falling asleep. Restless legs syndrome is usually not painful, and the symptoms last longer than night leg cramps do.

Other health issues can sometimes be linked to night leg cramps.

Common causes

1. Dialysis
2. Dehydration
3. Lack of physical activity
4. Medicines, such as birth control pills and those used to treat blood pressure and high cholesterol
5. Muscle fatigue
6. Pregnancy

Endocrine and metabolic conditions

1. Addison's disease
2. Anemia — a condition in which the body doesn't get oxygen due to a lack of healthy red blood cells
3. Chronic kidney disease
4. Hyperthyroidism (overactive thyroid)
5. Hypoglycemia
6. Hypothyroidism (underactive thyroid)
7. Type 1 diabetes
8. Type 2 diabetes

Neurologic conditions

1. Parkinson's disease
2. Peripheral neuropathy
3. Spinal stenosis

Vascular conditions

1. High blood pressure (hypertension)
2. Peripheral artery disease (PAD)

Other medical conditions

1. Alcohol use disorder
2. Cirrhosis