Waking suddenly with a painfully tightened calf can be alarming. One moment you are asleep; the next, a muscle in your leg feels as though it has twisted itself into a hard knot.
These episodes are known medically as nocturnal leg cramps. They are sudden, involuntary muscle contractions that occur while a person is resting or sleeping. The calf is affected most often, although cramps can also occur in the feet or thighs.
A cramp may last only a few seconds or continue for several minutes. Even after the muscle
relaxes, tenderness or soreness can linger for hours and occasionally into the following day.
Nighttime leg cramps are common, particularly with increasing age and during pregnancy. Most are harmless, and in many cases there is no clearly identifiable underlying cause. Still, frequent cramps can disrupt sleep and sometimes point to a medication effect or health condition that deserves attention.
