Magnesium, I personally believe, is probably more important than calcium in terms of how it impacts the health of the body, although magnesium and calcium along with potassium can significantly lower blood pressure.  Magnesium regulates over 300 different enzyme systems in the body and has a powerful effect regulating heart function.  It also controls tics, tremors and the relaxation of muscles.  People who have restless legs when sleeping can experience significant benefits supplementing with P-5-P and magnesium.  Magnesium is an excellent anti-stress mineral or for those who experience excessive nervousness.  When someone jumps from the slightest noise or is frightened easily, look for a magnesium deficiency.  Magnesium is a natural calcium channel blocker reducing plaque from the arteries and it supports the entire cardiovascular function.   Some of the symptoms associated with magnesium deficiency are grouped as neuromuscular disturbances;  Tetany (involuntary contraction of muscles), convulsions, ataxia (failure of muscular coordination), and tremors, behavioral disturbances, depression, irritability, and psychosis.  Increased risk of magnesium deficiency can be seen in individuals who are taking diuretics and those who drink alcohol excessively.  Toxicity of magnesium is rare since large quantities are hydroscopic and will cause diarrhea.  Upon increasing your magnesium content, if you experience diarrhea, just reduce the dosage to avoid causing diarrhea.  For many people magnesium is an excellent laxative.  It is safe, can be regulated easily by the symptoms and does not cause any harsh purging of the colon.  Many herbal laxatives or prescription drugs cause diarrhea by irritating the lining of the colon.