I have had really bad leg cramps all my life (since puberty, I think, even before) but since I started taking calcium regularly (or when I remember) the cramps have gone. If I remember, I take capsules that have 333 mg. of calcium and 167 mg of magnesium, one twice a day and during PMS week, I double it. It helps with the leg cramps, I seem to sleep better and theoretically, is supposed to help with those insane carb cravings I get during PMS week.