Nocturnal leg cramps are sudden, involuntary
contractions of the calf muscles that occur during the
night or while
at rest. Occasionally, muscles in the soles of the feet also become cramped. The sensation can last a few seconds or up to 10 minutes, but the soreness may linger. The cramps can affect persons in any age group, but they tend to occur in middle-aged and older populations. Dehydration is one common cause of leg cramps. Potassium and calcium intake are another factor.