I purchase this product to my mother-in law who is 81 years old. She has heart and thyroid gland condition. She has been complaining of legs cramping and poor sleep. Since she is on numeral medication, we added magnesium to her daily dose and within couple of days sleeping improved so she does not have to take any sleeping pills. Her legs cramping only returns when she forgets to take her drops for couple of days or so. I am planing to buy more of any magnesium product. It works!