I get these cramps only at night. My doctor prescribed quinine sulfate which I take every night. Sometimes it doesn't work. Like last night. Owee. I was up 4 times. Sometimes I apply heat and the cramp subsides. Mostly though, no one knows what causes them or what can be done about them. I have tried the calcium, the potassium, the sodium things. I wear socks to bed. It is good to know that there are others who suffer this same malady. At least I am not alone. If anyone finds a remedy that works consistently. Pass it on. Funny these things happen mostly at night, eh?