Nocturnal Leg Cramps Causes

Nocturnal leg cramps cause painful involuntary contractions in the leg muscles. The British Journal of General Practice reports this condition as a common and disruptive disturbance that affects a significant number of people over the age of 60; however, leg cramps can happen to anyone. The exact cause of nocturnal leg cramps is unknown but often relates to an underlying medical disorder. The risk of this disturbance increases with age, and pregnant women also have a higher incidence of leg cramping.


A metabolic condition known as hyponatremia may cause nocturnal leg cramps. Hyponatremia refers to depletion of sodium in the blood. The National Library of Medicine explains that sodium, an electrolyte, maintains blood pressure and aids muscle functioning. Electrolytes are minerals that the body needs to regulate water, maintain blood flow and move molecules in and out of cells. When the sodium levels in body fluids drop, water moves into cells to balance sodium concentration. The imbalance of sodium and fluid between the blood and the cells causes cramping and may also lead to symptoms of weakness and restlessness in the legs. Drinking fluids containing electrolytes may prevent cramping; however, if symptoms persist, patients require medical evaluation.


According to the Mayo Clinic, dehydration occurs when fluids are excreted, or released, from the body faster than a person takes them in. Water and other water-based fluids such as blood aid the body in staying hydrated for normal functioning. Engaging in strenuous physical activity or staying in hot temperatures without drinking adequate fluids may lead to dehydration. Dehydration may also lead to an imbalance in electrolytes. Leg cramping, muscle weakness and decreased urine output signify possible dehydration. Severe cases of dehydration often require hospitalization.

Restless Leg Syndrome

Restless leg syndrome, or RLS, causes discomfort in the legs, with prominent cramping, weakness and restlessness, especially at night. The National Institute of Neurological Disorders and Stroke indicates that RLS is a neurological disorder that may occur owing to anemia or chronic diseases such as diabetes. Triggers for nocturnal leg cramping associated with RLS include long periods of inactivity and excessive stretching.


The National Library of Medicine indicates that certain medications may cause leg cramping. Diuretic medications, also called water pills, rid the body of sodium and water. Although used for medical purposes, prescription diuretics tend to dehydrate the body and decrease electrolyte levels. Statins, medications that lower cholesterol, also increase the risk of leg cramping. Patients who experience leg cramps related to the use of these medications should speak with their physicians.

About this Author

Aureau Walding has been a contributing writer for online journals about health and mental-health topics since 2005. Walding has published health and fitness articles for LIVESTRONG.COM since 2010. She received her master’s degree in clinical social work and a Ph.D. in health psychology from the University of Missouri Kansas City.