This thread made me think of a question I've been meaning to ask for awhile.

Does anyone wake up in the middle of the night due to intense muscle cramps?

I get them in my calf muscles, only unilaterally. The cramp is so painful that it jolts me out of sleep and leaves me clutching my leg in intense pain for at least 30 agonizing seconds. The muscle is completely hard and contracted. I cannot move my foot or massage out the cramp because it only causes more pain - I have to just wait until it subsides on its own.

I've heard some people say that eating more potassium will help, but I'm wondering what causes these cramps and if anyone else gets them.