Leg cramps at night (also called nocturnal leg cramps) are a common and frustrating condition. The good news is that for most people, it is not a sign of significant illness and it tends not to get worse over time. The bad news is that there is usually no identifiable cause and treatment is often not completely effective. Here is what we do know:

• The reason muscles cramp in this condition is that the nerve fibers supplying the involved muscles are overactive. Why this happens is not clear, but it leads to accumulation of calcium in muscle cells, and that impairs their ability to relax.
• While the specific cause of leg cramps is usually unknown, they are occasionally associated with abnormalities in the lower leg (such as flat feet or overly flexible knees), prolonged sitting, dehydration with salt depletion (as with exercise or diuretic medications), low blood calcium or magnesium levels, and diabetes.
• A number of medications may be associated with muscle cramps, including diuretics and some asthma and chemotherapy medications.

Treatment for nocturnal leg cramps depends on whether a cause can be identified. For example, your health-care provider may recommend changing medications, taking extra calcium, or drinking more fluids. When no cause can be found, a number of approaches have been proposed, none of which are uniformly effective. These treatments include stretching or even light exercise before going to bed, heat (for example, a hot shower before bed), regular daytime exercise, good hydration, and improved footwear. Medications that may be effective include quinine, Benadryl, vitamin E, muscle relaxants, verapamil and gabapentin. Most of these have not been definitively proven to reduce cramps but, with appropriate medical supervision, one or more of these may be effective and acceptably safe.

Before starting any treatment, it is important to see your health-care provider to be sure there is no other explanation for your symptoms and to check for some of the conditions associated with leg and foot cramps.