I am caregiver to my mother who is 87. Besides PD, she has osteoporosis and has suffered through three compressed vertibrae. She has taken supplemental calcium most of her adult life but increased the amount after experiencing the first v. compression. She takes 1500 mg of calcium with magnesium everyday. On the odd night that she wakes up with muscle pain, I give her 500 mg. additional calcium and in a few minutes the pain is gone and she can get back to sleep. Next time she has muscle pain I'll try heat while I prepare the calcium. (she can not swallow the capsules so I open them and mix them with apple sauce or something simular. I know the calcium works. I believe that there must be an increased need for the mineral at least in her case. I have used it for minstral cramps and leg cramps and it was the first thing I thought of when she first began to experience these night time leg cramps. Carol Brow Lake Leelanau, Michigan and Winter Haven, Florida