I bought this to make sure I have enough magnesium and to help me sleep. It doesn't seem to help with my insomnia like it does others. But, it is supposed to relax the heart so I gave it to my husband to use because his Isosorbide and his Nitroglycerine weren't completely helping him with his unstable angina. Since giving him the magnesium (2 tabs at night), he has not had anymore Chest pain. He still takes the Isosorbide but hasn't needed the nitroglycerine. I was hoping it would work but wasn't sure. I am pleasantly surprised