Sudden night leg cramps occur when the muscles in your lower leg involuntarily contract and tighten (called a “spasm”), often without warning while you are sleeping.  Leg cramps at night are often confined to the calf muscles, but some people also feel their thigh or foot muscles cramping.   Night or nocturnal leg cramps in the calf are also known as Charley Horses.  These leg cramps do no permanent damage to your body, but they can be harmful from a psychological perspective.  Sudden night leg cramps cause severe pain in some cases and can greatly diminish the quality of sleep for …