Nocturnal leg cramps are sudden, involuntary contractions most commonly of the calf muscles during the night or during periods of rest. The cramping sensation may last a few seconds or up to 10 minutes, but the pain from the cramps may linger for a longer period. Nocturnal leg camps tend to be found in middle-aged or older populations, but people of any age can have them. Nocturnal leg cramps differ from restless leg syndrome as the latter usually does not involve cramping.
The cause of nocturnal leg cramps is not known. Some cases of the disorder can occur without a triggering event, while other causes of leg cramps may be linked to prolonged sitting, dehydration, an overexertion of the muscles, or structural disorders (such as flat feet). Muscle-stretching, exercise and adequate water intake may help prevent leg cramps. Some physicians suggest an increase in minerals such as calcium, magnesium and potassium.